wavelets of cigarette smoke drifted across the comfortably lounging enlisted men in the air-conditioned compartment of the fleet ballistic missile submarine, as they sat watching barney. sweat streaming from his swollen-veined forehead, hurried and grotesque in his black rubber diving suit, exploding triumphant curses like underwater demolition charges, barney finished tightening the control cables of what resembled a torpedo with two open cockpits. "this time the little gal raises her hydroplanes!"

at this contrast of men, the murderer had to grin, but carefully in order not to sweat and ruin the insulating qualities of his three woolen layers of longjohns. the submariners seemed quiet-talking and cooperative, as well adjusted as sardines in a can. the diver, barney, was foul-mouthed and fiercely individualistic, a wonderful guy—his diving buddy.

a legend in his own time, barney was reputed to have arisen from the mine-strewn waters of the korean coast at the time of the wonsan-inchon landings to give advice to general macarthur.

as an underwater demolition team diver, barney dated clear back into the murderer's childhood recollections of world war ii, to dim names like kwajalein and guam, where former seabees became combat divers to wire and blast japanese underwater obstacles and leave welcoming signs for the marines.

barney was only quiet about two things, his age and his circumference. he still fancied himself a baseball catcher, and his stubby fingers showed the deleterious effects of grabbing at foul tips with a bare hand, but those same fingers could expertly repair a wristwatch and the automatic transmission of an admiral's car and hock one and "borrow" the other.

barney had managed to put his homely younger sister through college and was now maneuvering to marry her off to a lieutenant commander on the staff of admiral rickover. and he could expertly joke the fears out of his diving buddy.

winking at his comfortably smoke-filled audience, barney dumped a sack of non-magnetic tools into the forward cockpit of the minisub he personally had built, and cocked his head.

"murderer, here, is hoping the villain is a sea serpent. don't laugh, you sea horses. the latest scuttlebutt from alaska has it that every time a picket buoy goes dead out here under the ice, the last sound it broadcasts is a sort of toothy crunch."

he pushed the joke a little further. "turn your periscopes on the blade murderer's wearing! john paul jones used to issue those for cutlasses! murderer's hoping to fight the sea serpent hand to hand."

his grin widening with embarrassment, the murderer felt called upon to retort. "i'll give you a better suspect for stealing our picket buoys. santa claus. these are his territorial waters. are you aware that in the middle ages santa claus was the patron saint of thieves?"

"now, mr. college boy," barney began, "you just want to show us you also studied history, not just marine biology. this boy will even tell you a long latin name for a little something that floats like dandruff in the water." a touch of pride appeared in barney's voice. "he can tell you its whole life history and what eats it and why it's important and why it will be a lot more important fifty years from now when your kids will need a lot more food from the sea."

there was a perceptible slowing, and the weird sound from the atomic submarine's heat-exchanger muted. barney glanced at his pressure-proof watch. the murderer tensed.

"this college boy may look like a tennis player," barney went on as if nothing had happened, "but in the water, when murderer sees something swimming down there, he doesn't care how big it is. we were installing the broadcast aerial from a picket buoy up through ice, and murderer had just retracted the magnesium flare pole, so i'm half-blinded. i look down. i see something so big i want to get out of there on a bicycle. but down murderer swims with the magnesium flare in one hand and his cutlass in the other. it's a shark as big as a small whale. the flare hypnotizes it, and round and round they go, with murderer stabbing away, letting in sea water, until that shark bugs out of there like a bare-bottomed boy from a swarm of bumblebees!"

the murderer studied his depth gauge to cover his embarrassment. the reason the shark had been so big was that it belonged to a species with the whale-like habit of straining the water for minute crustaceans. it was harmless and had winced from his first thrust. then its shagreen hide had tensed to armor-toughness, and it had been like trying to stab a submarine. it left because it had no reason to stay.

"i'm relieved," one of the submariners laughed, "that stabbing fish is how he got the name murderer."

"not only fish," barney went on enthusiastically. "this boy almost got himself court-martialed. we're working from the icebreaker, out from point barrow, diving from a whaleboat, and before the annapolis ensign can say a word, murderer's over the side. we put our face-plates in the water. he's bubbling down on a walrus! i swear, he rides it like a bucking horse. you need a long blade in the arctic. and ugly—when we bent a cable to that walrus from the icebreaker, the walrus stalled the winch!"

"what about tusks?" a submariner's voice asked.

the murderer had been well aware of tusks. for three days he had been studying the walrus herd with fascination. these staring-eyed, noisy mammals were living in icy water that would numb and kill a man in a few minutes.

some of them were diving to clam beds more than two hundred and fifty feet down, where their bodies were subjected to a pressure of more than eight atmospheres. in shallower water, where cockles predominated, he had actually observed them raking the muddy bottom with their tusks and rising with great disintegrating masses of mud and shells between their flippers. few men had ever seen that.

he marveled at the evolutionary process by which some primitive land mammal of the eocene period had become the walrus.

why he had swum down and attacked a walrus, he did not know. afterward he felt ashamed, not just because it was a dumb thing to do and he'd had three ribs cracked and should have been killed; not because it was a show-off thing, with sailors urging him to stand in front of its hoisted body so they could take pictures for their girl friends; not because barney lost his appetite for a couple of days and didn't seem very eager to dive near the herd. what bothered him was the indescribable feeling he'd had as he swam down with his knife to the walrus, a feeling closer than hunger....

"when we get back, i'll show you the photographs," barney was insisting proudly. "when they assigned this boy as my diving buddy, they sent his name along, murderer. if it swims. murderer will go down after it, they said. and they weren't lying."

but that was not how the name originated. sitting there in the drifting cigarette smoke, feeling the sweat soak through his longjohns, the murderer wished the submarine's commander would hurry up and decide on a position, let them out of the boat, get it over with.

probably by now, even the guys who were in u.d.t. training with him believed he got the name by murdering fish.

they gave the name to him, but it was during an orientation meeting with diagrams and graphs and talk of megatons and current-borne radioactivity and a model of an atomic depth charge on the table. an incredulous revulsion had come over him, this mindlessly mechanical can of death that could poison, could make useless two billion struggling years of life, all wasted, single-celled ancestors, diatoms, copepods, wondrous fish.

during the discussion, he had kept exclaiming: "it's murder! it's murder!" this was how he had acquired his name.

"hey, murderer," one of the submariners laughed. "you should cut off a sea serpent steak for the skipper. i bet he'd go for one."

"speaking of murderers," the murderer blurted, suddenly detesting the name, raising his clean-cut, angrily intelligent face, flooding his longjohns with angry sweat, "you all are potential murderers—on a big scale. let's say ten thousand victims apiece. i kill a few fish, so i'm a murderer? but you are all gears and cogs of a mass production murder mechanism called a fleet ballistic missile submarine. an impersonal machine that—"

"not impersonal," the commander's voice said clearly as he came into the compartment. "this boat is just another tool for survival—like a shield or spear. men make the decisions for it."

barney said in an attempt to ease the tension, "you want us to bring you any ice cubes, commander?"

the commander's gray eyes studied barney's red-veined ones. "just bring yourselves back, barney. we'll settle for that." he touched the minisub. "all i can say is we think we're in the sector where the picket buoys shorted out. there've been such meager appropriations for hydrographic surveys in the arctic ocean, we haven't a very clear picture of fathometer landmarks even in this sector. so the navigator has depended pretty heavily on his dead reckoning and inertial navigation. what i'm getting at is don't spend too much time looking. use conservative search patterns. give yourself plenty of margin to find your way home to us. we'll do our best to hold this position."

slowly, the commander smiled. "we'll keep the coffee hot until you get back."

the murderer watched them roll the minisub along on its cradle and into the chamber. from the stern, the minisub looked less like a torpedo. instead of the compact round propeller blades associated with high speeds under water, the minisub had long narrow blades which might have looked more appropriate on a wright brother's airplane. these would unwind through the water so slowly there would be no cavitation, no tell-tale bubbling sounds.

"one last thing," the commander said, including the murderer in his gray gaze. "no aggressive action. if you should meet—someone—break off contact in a dignified manner and come home."

strangely, the commander smiled again and glanced at his watch. "right about now, my two kids are waking from their afternoon naps and running out into the backyard in their underpants to swing on the swings. no aggressive action, o.k.?"

the murderer felt thankful he was not the commander—with the responsibility for sixteen hydrogen-warheaded polaris missiles on his back.

weighted down by his air tanks, the murderer crawled into the chamber beside the minisub and reached into the stern cockpit. he unreeled a few feet of the red wire and plugged it into the chest socket of his electric suit warmer. out there, you couldn't search very long without battery heat from the minisub.

automatically checking his full-face mask, he connected with the black wire and tested his throat mike, earplug circuit. "one—two—three—"

"four—shut the door," barney's voice croaked weirdly. for complicated two-man disassemblies underwater, the traditional hand signals were not enough. the minisub acted as a telephone exchange.

turning from the minisub, barney plugged into the telephone connection in the wall of the chamber, giving them the word. from the way the arctic ocean, fire-hosed into the chamber, the murderer guessed they had at least a hundred feet of water standing on them. this captain had no intention of smashing his periscopes on pack ice.

wryly, the murderer grinned while the water crept up his body. he knew the limiting factor in their search for a picket buoy, any picket buoy, was the survival time in their air tanks. as for the minisub, it had the capability of keeping their corpses warm for several hours thereafter. with its gyroscope efficiently clicking commands to the rudder, it would maintain a straighter course than any man could steer. if it could eat fish and reproduce itself....

the waterline rose above his glass face-plate. on the curved ceilings of the chamber, the air shrank into a squirming bubble. the pressure had been equalized. there was a cold metallic screech as barney opened the outer hatch into the arctic ocean.

valving an additional hiss of compressed air into the minisub's forward flotation tank, the murderer gave it a gentle push and rode it out, his hand on the air release valve now to prevent the increasingly buoyant minisub from falling upward against the white-glaring underside of the ice pack.

"there's a hell of a current up here," barney's voice croaked.

the murderer glanced down, and his free arm clutched the cockpit in an anthropoidal fear-reflex of falling. the water was that clear. down there, the submarine seemed to drift away like a great dirigible in the wind, but the murderer knew the minisub was actually doing the drifting.

"tinker carefully with your gyroscope, mr. navigator," barney laughed, "and we'll go take a look for your sea serpent."

he gave barney a straight course into the current. the murderer had had nightmares of being lost under the arctic ice pack.

"keep an eye peeled on the ice," barney muttered, but the murderer kept both eyes on the instruments and gave barney a one-hundred-eighty-degree change of course, trying to determine the speed of the current.

"one way's as good as another," barney laughed.

unfortunately, this had to be a visual search. the drawing-board boys had designed the picket buoys so they would not be detected, and thoughtfully made them self-destroying in case they were. if anywhere near, a submarine would be recorded, and the under-ice warning system had actually worked against their own submarines. but the picket buoys in this sector, one by one, had died without a warning sound except, as scuttlebutt would have it, a toothy crunch.

"this pack ice has changed," barney's voice muttered.

barney and the murderer had been one of the diving teams out there when a submarine ejected the buoys beneath the polar ice. a buoy would squirt from a torpedo tube. when the non-magnetic float struck the underside of the ice, metal rods clutched upward like the legs of a spider clinging to the ice. a thread-like cable lowered the tiny instrument capsule into the depths. the capsule's small size was intended to foil typical mine detection sonar, while the float was supposed to merge with irregularities of sonic reflection on the underside of the ice. some admiral had even ordered the floats painted white, but they still cut off light and appeared dark from beneath the ice.

after the divers had melted a quick hole through two or three feet of pack ice and extended the whip-like aerial into the polar air, headquarters could keep track of the drifting buoy's location. intermittently, for the classified number of years the batteries were supposed to last, each buoy would broadcast its own identification code, only coming through with a high wattage warning when its instrument capsule in the depths of the arctic ocean was awakened. the joker here, the murderer thought, was that the aerials might be hard to see, but any simple fool could make himself a radio location finder. live buoys could be hunted from the surface ice.

"how dry i am," barney's voice croaked unmusically, "how dry i be, nobody knows—nobody cares—"

now the white underside of the ice drooped in downward bulges, indicating thicker masses of old ice that had been frozen into the pack. the murderer saw the gray outline of driftwood entombed in this old ice.

"drift ice from the siberian rivers," barney croaked. "when we planted the picket buoys, our sector didn't have any of this."

the murderer looked down at his instruments, preparing to change course.

"my god, look!" barney's voice croaked, and his black rubber arm pointed upward.

the murderer's breathing stopped as he made out something quivering up there. "what is it?"

"animal, vegetable or mineral," barney wheezed. "if it's animal, i don't want to be around when whatever laid these eggs comes back."

swaying up there on the underside of the ice in a gelatinous mass at least twenty feet across, it resembled a mass of gigantic frog's eggs.

but the murderer decided there was too great a variation in size for them to be eggs. those nearest the outside of the mass seemed clearer, more transparent, than the surrounding gelatinous substance. the murderer's excitement began to fade.

"they're not eggs," he said disappointedly. "i think they're only bubbles encased in some sort of soft plastic."

"mineral," barney said with some relief in his voice. "now i see that dark part in the middle has the shape of a can. the bubbles must be to float a mine or secret mechanism," his voice ended excitedly. barney wanted nothing to do with live things; he liked mechanical devices that clicked and buzzed and could be taken apart and then put back together.

he eased the minisub up toward the gelatinous mass.

"don't bring the minisub too close," the murderer gasped, imagining a mechanical click as the impersonal gadgetry within the can detected their approach and cocked the lifeless steel prongs of a detonator.

barney laughed in excited contrast. "even our air tanks are non-magnetic. or if it's hydrophonic, the noise level to set it off would have to be plenty high, because of all the crunching sounds every day in the ice. i'm going to find out what it is."

barney rose from his cockpit, trailing his green-stained canvas bag of non-magnetic tools.

"you're not going to cut into it, are you?" the murderer cried.

"that's what the taxpayers pay me for—to protect them from—you name it. murderer, you sail the minisub off until all my telephone cable is out. just like when we practiced disarming our picket buoys, i'll tell you every move i make."

"if it's a mine," the murderer said, "i'll be as flattened as you."

"take notes on your navigational pad. i'll start with a little experimental cut into the jello. we can't go off and leave this thing; we'd never find it again. and it wouldn't be exactly smart to tow it to our submarine until we know what its insides are supposed to do."

barney's black rubber arm was sawing vigorously up and down. "this jello's tougher than it looks. very ingenious. i'll bet this was a compact little bundle when a submarine ejected it into the water. probably sea water makes it swell—and chemicals fizz inside so that the bubbles appear and float the can up to the underside of the ice.

"this is important," barney's voice croaked on. "i've come to some thin shiny wires. they seem to be all through the jello and to curve back in toward the can."

the murderer clenched his hand. he could feel the tendons and imagine the wonderfully intricate nerves of his living hand. he'd been frightened many times under the sea. occasionally divers talked about which way they'd rather go. nitrogen narcosis was popular among the heavy drinkers. barney's choice—a nice close mine explosion because it would be so quick. they thought the murderer was crazy when he said he'd rather be eaten by a great white shark than smashed by some miserable explosive gadget.

"now i'm spreading two wires apart," barney said calmly, "but i've left a layer of gelatin around each of them. i will not cut the wires and i'll try not to let them touch each other."

gradually his head and shoulders disappeared up into the gelatinous mass.

"don't snag your tanks or regulator on a wire," the murderer breathed.

"now i'm cutting within a few inches of the base of the can." only barney's kicking legs showed. "my air is filling the cut—and i'm going—to open a—chimney." bubbles emerged from the side of the swaying mass.

"suppose this thing is atomic," the murderer said. "it would crush our ballistic missile sub from here."

"this is peacetime, boy. nobody's fool enough to let an atomic mine go drifting around with the ice."

the murderer looked down at the hard metal shell of the minisub. you could blast and smash it, and it would still be metal. you even could vaporize it, and its atomic particles would be somewhere—or changed into energy—but nothing really lost, because it had never been alive. the murderer thought of the commander's two kids waking from their naps. it had taken life two billion years to get that far, and it all could be lost. right now, was barney committing aggressive action?

he thought again of that orientation class where they theoretically learned how to disarm an unexploded atomic depth charge. he had expressed his feeling that these atomic charges were murder. the fools had laughed and begun calling him murderer.

"the bottom of this can is as blank," barney said, "as a sailor in one of those modern art museums. i'm going to cut my way along the side of the can and see what i can see."

a little fish, perhaps lost from its school, peered into the murderer's glass face-plate. its wondrous eye grew inquisitively larger, and he thought of the millions of cooperating cells that made up its eye and optic nerve and receiving brain and the marvel that the individually drifting cells of two billion years ago could have achieved this.

there was a contradiction, he thought. he was amazed by life and yet he speared fish. did he enjoy feeling life wriggle on the end of his spear?

"i've reached the top," barney's voice croaked. "there's a rod here—get this, a vertical rod. it extends up into the ice like with the aerials of our picket buoys. i knew it wasn't a mine. this is how they plan to detect our atomic submarines. this will make a very interesting present for admiral rickover—"

at this instant there was a darkening slap against the murderer's mask. his eardrums burst inward. his intestines squeezed up into his chest from the force of the underwater explosion. he blacked out.

ice water seared his face. he was drowning. convulsively, his hand groped for his mask. the glass was intact. his hand dragged the mask back to a proper fit upon his face, and compressed air forced out the sea water. he could feel the telephone cord pulling at his mask.

everything was blinding white, and he realized he was belly up beneath the ice. "barney?"

the telephone wire began to drag him down head first, and he went down it hand over hand toward the slowly sinking minisub. "barney?"

further down, he saw barney's black rubber suit spread-eagled and sinking, and he swam clumsily down past the minisub. he clutched barney's black rubber arm and dragged it toward the minisub. the black rubber suit seemed to have no bones. everything drooped and swayed as he tried to fit barney into the stern cockpit. when he wrapped barney's wires to tie him in, they came face to face. there was no glass in barney's mask. the glass had burst where the face had been.

murderer's eyes narrowed in helpless rage at barney's death.

dragging himself into barney's forward cockpit, he valved air into the minisub's forward flotation tank, raising the torpedo-like nose. it was then that he saw them up there, silhouetted small and frog-like against the blinding white ice, two divers.

the two silhouettes were looking down at him, and he knew they had been attracted by the explosion of their gelatinous picket buoy. he looked all around for the dim gray outline of their submarine, but there was no sign of their "home," and his gaze concentrated with wide-eyed intensity on their black paddling shapes as his minisub rose from the depths.

he saw them exchange hurried hand signals. they began to swim away, side by side, their fins fluttering rapidly now. they were swimming a definite course, and still there was no sign of their submarine as his minisub inexorably gained on them.

now that he had reached their altitude, he noticed they were already tiring. one diver looked back, then swam frantically to catch up with the other. like a slow fighter plane, the minisub came in on them from behind, and one diver pushed at the other. they again exchanged hand signals, losing yards to the minisub, and one began to swim hard while the other turned back, facing the minisub, raising his hand in what appeared to be a courteous military salute. the minisub kept coming straight at him.

then the diver spread his arms in a gesture of peace. the minisub's torpedo-shaped nose rammed his belly. unsheathing his long blade, the murderer struck.

as the diver wriggled, the murderer withdrew the blade and struck again. air bubbles streamed from the diver's chest with each exhalation of breath as he backwatered. his expression seemed mild surprise as the murderer struck a third time, driving the blade down between the man's neck and collar bone, pushing him deeper. the next blow smashed the mask. belatedly, the man's hand flurried, seeming to clutch at his bubbles as he sank.

the murderer looked up. far off under the ice, the other diver had stopped, was looking down, watching, and the murderer held up his blade as a signal and turned the minisub upward, after him. this diver took evasive action among the downward bulges of old siberian ice and suddenly vanished.

although there was no sky glare in the water, the murderer supposed the diver had found an open lead in the ice and would rather freeze to death, or at least put up a fight from the edge of the ice, than die in the water.

valving more air into the minisub's flotation tanks, the murderer steered it rapidly up into the oddly round, oddly dim lead in the ice pack. at the edge of his mask-vision he glimpsed a longish tubular shape suspended in the water, but the minisub was rising too fast for him to get a good look. the overbuoyant minisub bloomed above the surface and sloshed back, rolling unsteadily while the film of water slid off his mask without freezing and he saw.

the white blur became the biggest twin-rotored copter he had ever seen, squatting there on the ice, white except for its glass. then his eyes were attracted by motion, by the parka-clad men hauling the surviving diver up on the ice. other darkish figures were simply standing there, some of them beginning to point.

behind them was a smaller helicopter with the loop-shaped aerial of a radio location finder mounted atop its plastic dome. there was something wrong with the sky, and the murderer realized it was not the sky. it was a vast white canvas dome, dimpling in the polar wind. the unnatural circle in the ice and the equipment grouped around it all were hidden from aerial observation.

pointing at him from the fuselage of the huge helicopter, and so close that his eyes had avoided it, was a metal boom with a hoist cable taut into the water, tethering something below the surface. some of the men were running toward the huge helicopter now. in front of them at the edge of the ice lay shapeless bundles of what appeared to be black rubberized canvas, and he wondered fleetingly if these contained more of the soon-to-be gelatinous picket buoys. one of the figures was aiming something at him. as the murderer let air out of the flotation tanks and swiftly sank, he realized it had not been a gun; it had been a camera with a telephoto lens.

he passed the tubular shape on the end of the cable. it was an anti-submarine torpedo. when he sank deeper, he passed a cylinder dangling from two black rubber-insulated cables.

he valved compressed air back into the flotation tanks and came up under the ice, so hazardously close he had to duck his head as he steered a weaving course among the downward bulges of old siberian ice. even though he had been deafened, he felt the sonar pulsing against the ice, searching for him. then he felt it knocking against the minisub, pinging against his air tanks, thudding accusingly against his bones. it followed him wherever he steered.

he smiled blearily. this would be the ultimate if they unleashed the expensively intricate homing torpedo—at one man riding a cheap minisub constructed by a big-handed, happily singing petty officer on his own time. he hoped they would waste the torpedo on him. if he had to be destroyed by a gadget, an infernal machine, at least it was better to be killed as an individual rather than in a group so large he would be nameless in death.

abruptly the sonar left him. they must have decided he was not going to lead them back to his submarine. now they were hurriedly ranging for it.

he cruised on and on with his dead cargo.

then he felt the echo of sonar from the submarine's hull. he must be close. the helicopter, with its sonar system lowered into the water like a fisherman's hook, had caught the fleet ballistic missile submarine.

he could feel the submarine's sonar searching frantically. they would be sounding for another submarine. he could imagine horror on the sonar men's faces as they realized they couldn't detect anything at the apparent source of the unidentified sonar that had caught them.

the submarine's sonar caught something—him.

he steered directly into it and found the submarine. bow into the current, the gray undersea boat was still holding its position. the murderer guessed the commander had decided that the best move was no move.

valving out air, he brought the minisub down, opened the outer hatch and dragged the minisub into the water-filled chamber. a great weariness had come over him and it was all he could do to lock the hatch. he knocked on the bulkhead, while the persistent sonar pinging went on and on. someone tapped very gently, although they might as well hammer with a wrench; it wouldn't make any difference now. the murderer realized they were waiting for him to plug into the telephone socket and give his maximum depth and time spent there and other decompression data he hadn't kept. they intended to decompress him as if this were just another safe-and-sane training exercise.

in the chamber lights, barney's rubber suit had sagged over the side of the minisub like a black rag doll. the murderer averted his eyes and plugged in.

"one—two—three—" he said automatically.

"barney?"

"barney's dead."

"this is the commander. there is a submarine out there. for some reason, we can't locate it with our sonar. have you seen it?"

"commander, it's a helicopter. they have an anti-submarine torpedo in the water."

"i'm having difficulty reading you—"

"helicopter. anti-sub torpedo!"

"did they take any aggressive action against you?"

"depends on how you look at it. their picket buoys are under here. barney tried to recover one. it was booby-trapped to destroy itself."

"barney?" the commander's voice persisted.

"i told you he's dead! i got one of their divers."

"one of their divers? he was attacking you?"

"i killed him. he was trying to get away."

there was a long pause. only the persistent knocking of the giant helicopter's sonar reached the murderer's ear.

when the commander spoke again, it was as if murder had been done. "do they know?"

"the other one looked back. sure they know. they know."

"then they may consider we're the ones who've taken aggressive action," the commander said slowly. "we'll have to wait. if we move off, their commanding officers on the spot may feel committed to local retaliatory action. we'll have to wait while they're radioing for instructions. we'll have to hope their side will decide to take this before an international court."

"court? what sort of court? a murder court?"

"let's hope it's only one murder," the commander's voice came through distantly, "and not one hundred million. we'll have to sit it out."

as decompression began, the murderer sank down beside barney's body in the water-filled chamber. superimposed upon the commander's two little kids, swinging on their swings, he saw the surprised face of the diver—and even the little fish, lost from its school, and its wondrous eye—two billion years of evolution waiting for a verdict of life or death.