within the minute that case was to be immeasurably strengthened. an exclamation broke from hanaud. he sprang to his feet and turned on the light of a green-shaded reading lamp, which stood upon the ledge of the bureau. he was holding now under the light a small drawer, which he had removed from the front of the bureau. very gingerly he lifted some little thing out of it, something that looked like a badge that men wear in their buttonholes. he laid it down upon the blotting paper; and in that room of death laughed harshly.

he beckoned to jim.

"come and look!"

what jim saw was a thin, small, barbed iron dart, with an iron stem. he had no need to ask its nature, for he had seen its likeness that morning in the treatise of the edinburgh professor. this was the actual head of simon harlowe's poison-arrow.

"you have found it!" said jim in a voice that shook.

"yes."

hanaud gave it a little push, and said thoughtfully:

"a negro thousands of miles away sits outside his hut in the kombe country and pounds up his poison seed and mixes it with red clay, and smears it thick and slab over the shaft of his fine new arrow, and waits for his enemy. but his enemy does not come. so he barters it, or gives it to his white friend the trader on the shire river. and the trader brings it home and gives it to simon harlowe of the maison crenelle. and simon harlowe lends it to a professor in edinburgh, who writes about it in a printed book and sends it back again. and in the end, after all its travels, it comes to the tenement of jean cladel in a slum of dijon, and is made ready in a new way to do its deadly work."

for how much longer hanaud would have moralised over the arrow in this deplorable way, no man can tell. happily jim frobisher was reprieved from listening to him by the shutting of a door below and the noise of voices in the passage.

"the commissary!" said hanaud, and he went quickly down the stairs.

jim heard him speaking in a low tone for quite a long while, and no doubt was explaining the position of affairs. for when he brought the commissary and the doctor up into the room he introduced jim as one about whom they already knew.

"this is that monsieur frobisher," he said.

the commissary, a younger and more vivacious man than girardot, bowed briskly to jim and looked towards the contorted figure of jean cladel.

even he could not restrain a little gesture of repulsion. he clacked his tongue against the roof of his mouth.

"he is not pretty, that one!" he said. "most certainly he is not pretty."

hanaud crossed again to the bureau and carefully folded the dart around with paper.

"with your permission, monsieur," he said ceremoniously to the commissary, "i shall take this with me. i will be responsible for it." he put it away in his pocket and looked at the doctor, who was stooping by the side of jean cladel. "i do not wish to interfere, but i should be glad to have a copy of the medical report. i think that it might help me. i think it will be found that this murder was committed in a way peculiar to one man."

"certainly you shall have a copy of the report, monsieur hanaud," replied the young commissary in a police and formal voice.

hanaud laid a hand on jim's arm.

"we are in the way, my friend. oh, yes, in spite of monsieur le commissaire's friendly protestations. this is not our affair. let us go!" he conducted jim to the door and turned about. "i do not wish to interfere," he repeated, "but it is possible that the shutters and the window will bear the traces of the murderer's fingers. i don't think it probable, for that animal had taken his precautions. but it is possible, for he left in a great hurry."

the commissary was overwhelmed with gratitude.

"most certainly we will give our attention to the shutters and the window-sill."

"a copy of the finger-prints, if any are found?" hanaud suggested.

"shall be at monsieur hanaud's disposal as early as possible," the commissary agreed.

jim experienced a pang of regret that monsieur bex was not present at the little exchange of civilities. the commissary and hanaud were so careful not to tread upon one another's toes and so politely determined that their own should not be trodden upon. monsieur bex could not but have revelled in the correctness of their deportment.

hanaud and frobisher went downstairs into the street the neighbourhood had not been aroused. a couple of sergents-de-ville stood in front of the door. the street of gambetta was still asleep and indifferent to the crime which had taken place in one of its least respectable houses.

"i shall go to the prefecture," said hanaud. "they have given me a little office there with a sofa. i want to put away the arrow head before i go to my hotel."

"i shall come with you," said jim. "it will be a relief to walk for a little in the fresh air, after that room."

the prefecture lay the better part of a mile away across the city. hanaud set off at a great pace, and reaching the building conducted jim into an office with a safe set against the wall.

"will you sit down for a moment? and smoke, please," he said.

he was in a mood of such deep dejection; he was so changed from his mercurial self; that only now did jim frobisher understand the great store he had set upon his interview with jean cladel. he unlocked the safe and brought over to the table a few envelopes of different sizes, the copy of the treatise and his green file. he seated himself in front of jim and began to open his envelopes and range their contents in a row, when the door was opened and a gendarme saluted and advanced. he carried a paper in his hand.

"a reply came over the telephone from paris at nine o'clock to-night, monsieur hanaud. they say that this may be the name of the firm you want. it was established in the rue de batignolles, but it ceased to exist seven years ago."

"yes, that would have happened," hanaud answered glumly, as he took the paper. he read what was written upon it. "yes—yes. that's it. not a doubt."

he took an envelope from a rack upon the table and put the paper inside it and stuck down the flap. on the front of the envelope, jim saw him write an illuminating word. "address."

then he looked at jim with smouldering eyes.

"there is a fatality in all this," he cried. "we become more and more certain that murder was committed and how it was committed. we get a glimpse of possible reasons why. but we are never an inch nearer to evidence—real convincing evidence—who committed it. fatality? i am a fool to use such words. it's keen wits and audacity and nerve that stop us at the end of each lane and make an idiot of me!"

he struck a match viciously and lit a cigarette. frobisher made an effort to console him.

"yes, but it's the keen wits and the audacity and the nerve of more than one person."

hanaud glanced at frobisher sharply.

"explain, my friend."

"i have been thinking over it ever since we left the street of gambetta. i no longer doubt that mrs. harlowe was murdered in the maison crenelle. it is impossible to doubt it. but her murder was part of the activities of a gang. else how comes it that jean cladel was murdered too to-night?"

a smile drove for a moment the gloom from hanaud's face.

"yes. you have been quite fifteen minutes in the bull-ring," he said.

"then you agree with me?"

"yes!" but hanaud's gloom had returned. "but we can't lay our hands upon the gang. we are losing time, and i am afraid that we have no time to lose." hanaud shivered like a man suddenly chilled. "yes, i am very troubled now. i am very—frightened."

his fear peered out of him and entered into frobisher. frobisher did not understand it, he had no clue to what it was that hanaud feared, but sitting in that brightly-lit office in the silent building, he was conscious of evil presences thronging about the pair of them, presences grotesque and malevolent such as some old craftsman of dijon might have carved on the pillars of a cathedral he, too, shivered.

"let us see, now!" said hanaud.

he took the end of the arrow shaft from one envelope, and the barb from his pocket, and fitted them together. the iron barb was loose now because the hole to receive it at the top of the arrow shaft had been widened to take a nib. but the spoke was just about the right length. he laid the arrow down upon the table, and opened his green file. a small square envelope, such as chemists use, attracted jim's notice. he took it up. it seemed empty, but as he shook it out, a square tablet of some hard white substance rolled on to the table. it was soiled with dust, and there was a smear of green upon it; and as jim turned it over, he noticed a cut or crack in its surface, as though something sharp had struck it.

"what in the world has this to do with the affair?" he asked.

hanaud looked up from his file. he reached out his hand swiftly to take the tablet away from jim, and drew his hand in again.

"a good deal perhaps. perhaps nothing," he said gravely. "but it is interesting—that tablet. i shall know more about it to-morrow."

jim could not for the life of him remember any occasion which had brought this tablet into notice. it certainly had not been discovered in jean cladel's house, for it was already there in the safe in the office. jim had noticed the little square envelope as hanaud fetched it out of the safe. the tablet looked as if it had been picked up from the road like monsieur bex's famous match-box. or—yes, there was that smear of green—from the grass. jim sat up straight in his chair. they had all been together in the garden this morning. hanaud, himself, betty and ann upcott. but at that point frobisher's conjectures halted. neither his memory nor deduction could connect that tablet with the half-hour the four of them had passed in the shade of the sycamores. the only thing of which he was quite sure was the great importance which hanaud attached to it. for all the time that he handled and examined it hanaud's eyes never left him, never once. they followed each little movement of finger tip and thumb with an extraordinary alertness, and when jim at last tilted it off his palm back into its little envelope, the detective undoubtedly drew a breath of relief.

jim frobisher laughed good-humouredly. he was getting to know his man. he did not invite any "aha's" and "oho's" by vain questionings. he leaned across the table and took up his own memorandum which hanaud had just laid aside out of his file. he laid it on the table in front of him and added two new questions to those which he had already written out. thus:

(5) what was the exact message telephoned from paris to the prefecture and hidden away in an envelope marked by hanaud: "address"?

(6) when and where and why was the white tablet picked up, and what, in the name of all the saints, does it mean?

with another laugh frobisher tossed the memorandum back to hanaud. hanaud, however, read them slowly and thoughtfully. "i had hoped to answer all your questions to-night," he said dispiritedly. "but you see! we break down at every corner, and the question must wait."

he was fitting methodically the memorandum back into the file when a look of extreme surprise came over frobisher's face. he pointed a finger at the file.

"that telegram!"

there was a telegram pinned to the three anonymous letters which hanaud had in the file—the two which hanaud had shown to frobisher in paris and the third which betty harlowe had given to him that very afternoon. and the telegram was pieced together by two strips of stamp-paper in a cross.

"that's our telegram. the telegram sent to my firm by miss harlowe on monday—yes, by george, this last monday."

it quite took jim's breath away, so crowded had his days been with fears and reliefs, excitements and doubts, discoveries and disappointments, to realise that this was only the friday night; that at so recent a date as wednesday he had never seen or spoken with betty harlowe. "the telegram announcing to us in london that you were engaged upon the case."

hanaud nodded in assent.

"yes. you gave it to me."

"and you tore it up."

"i did. but i picked it out of the waste-paper basket afterwards and stuck it together." hanaud explained, in no wise disconcerted by jim frobisher's attack of perspicacity. "i meant to make some trouble here with the police for letting out the secret. i am very glad now that i did pick it out. you yourself must have realised its importance the very next morning before i even arrived at the maison crenelle, when you told mademoiselle that you had shown it to me."

jim cast his memory back. he had a passion for precision and exactness which was very proper in one of his profession.

"it was not until you came that i learnt miss harlowe had the news by an anonymous letter," he said.

"well, that doesn't matter," hanaud interposed a trifle quickly. "the point of importance to me is that when the case is done with, and i have a little time to devote to these letters, the telegram may be of value."

"yes, i see," said jim. "i see that," he repeated, and he shifted uncomfortably in his chair; and opened his mouth and closed it again; and remained suspended between speech and silence, whilst hanaud read through his file and contemplated his exhibits and found no hope in them.

"they lead me nowhere!" he cried violently; and jim frobisher made up his mind.

"monsieur hanaud, you do not share your thoughts with me," he said rather formally, "but i will deal with you in a better way; apart from this crime in the maison crenelle, you have the mystery of these anonymous letters to solve. i can help you to this extent. another of them has been received."

"when?"

"to-night, whilst we sat at dinner."

"by whom?"

"ann upcott."

"what!"

hanaud was out of his chair with a cry, towering up, his face white as the walls of the room, his eyes burning upon frobisher. never could news have been so unexpected, so startling.

"you are sure?" he asked.

"quite. it came by the evening post—with others. gaston brought them into the dining-room. there was one for me from my firm in london, a couple for betty, and this one for ann upcott. she opened it with a frown, as though she did not know from whom it came. i saw it as she unfolded it. it was on the same common paper—typewritten in the same way—with no address at the head of it. she gasped as she looked at it, and then she read it again. and then with a smile she folded it and put it away."

"with a smile?" hanaud insisted.

"yes. she was pleased. the colour came into her face. the distress went out of it."

"she didn't show it to you, then?"

"no."

"nor to mademoiselle harlowe?"

"no."

"but she was pleased, eh?" it seemed that to hanaud this was the most extraordinary feature of the whole business. "did she say anything?"

"yes," answered jim. "she said 'he has been always right, hasn't he?'"

"she said that! 'he has been always right, hasn't he?'" hanaud slowly resumed his seat, and sat like a man turned into stone. he looked up in a little while.

"what happened then?" he asked.

"nothing until dinner was over. then she picked up her letter and beckoned with her head to miss betty, who said to me: 'we shall have to leave you to take your coffee alone.' they went across the hall to betty's room. the treasure-room. i was a little nettled. ever since i have been in dijon one person after another has pushed me into a corner with orders to keep quiet and not interfere. so i came to find you at the grande taverne."

at another moment jim's eruption of injured vanity would have provoked hanaud to one of his lamentable exhibitions, but now he did not notice it at all.

"they went away to talk that letter over together," said hanaud. "and that young lady was pleased, she who was so distressed this afternoon. a way out, then!" hanaud was discussing his problem with himself, his eyes upon the table. "for once the scourge is kind? i wonder! it baffles me!" he rose to his feet and walked once or twice across the room. "yes, i the old bull of a hundred corridas, i, hanaud, am baffled!"

he was not posturing now. he was frankly and simply amazed that he could be so utterly at a loss. then, with a swift change of mood, he came back to the table.

"meanwhile, monsieur, until i can explain this strange new incident to myself, i beg of you your help," he pleaded very earnestly and even very humbly. fear had returned to his eyes and his voice. he was disturbed beyond jim's comprehension. "there is nothing more important. i want you—how shall i put it so that i may persuade you? i want you to stay as much as you can in the maison crenelle—to—yes—to keep a little watch on this pretty ann upcott, to——"

he got no further with his proposal. jim frobisher interrupted him in a very passion of anger.

"no, no, i won't," he cried. "you go much too far, monsieur. i won't be your spy. i am not here for that. i am here for my client. as for ann upcott, she is my countrywoman. i will not help you against her. so help me god, i won't!"

hanaud looked across the table at the flushed and angry face of his "junior colleague," who now resigned his office and, without parley, accepted his defeat.

"i don't blame you," he answered quietly. "i could, indeed, hope for no other reply. i must be quick, that's all. i must be very quick!"

frobisher's anger fell away from him like a cloak one drops. he saw hanaud sitting over against him with a white, desperately troubled face and eyes in which there shone unmistakeably some gleam of terror.

"tell me!" he cried in an exasperation. "be frank with me for once! is ann upcott guilty? she's not alone, of course, anyway. there's a gang. we're agreed upon that. waberski's one of them, of course? is ann upcott another? do you believe it?"

hanaud slowly put his exhibits together. there was a struggle going on within him. the strain of the night had told upon them both, and he was tempted for once to make a confidant, tempted intolerably. on the other hand, jim frobisher read in him all the traditions of his service; to wait upon facts, not to utter suspicions; to be fair. it was not until he had locked everything away again in the safe that hanaud yielded to the temptation. and even then he could not bring himself to be direct.

"you want to know what i believe of ann upcott?" he cried reluctantly, as though the words were torn from him. "go to-morrow to the church of notre dame and look at the façade. there, since you are not blind, you will see."

he would say no more; that was clear. nay, he stood moodily before frobisher, already regretting that he had said so much. frobisher picked up his hat and stick.

"thank you," he said. "good night."

hanaud let him go to the door. then he said:

"you are free to-morrow. i shall not go to the maison crenelle. have you any plans?"

"yes. i am to be taken for a motor-drive round the neighbourhood."

"yes. it is worth while," hanaud answered listlessly. "but remember to telephone to me before you go. i shall be here. i will tell you if i have any news. good night."

jim frobisher left him standing in the middle of the room. before he had closed the door hanaud had forgotten his presence. for he was saying to himself over and over again, almost with an accent of despair: "i must be quick! i must be very quick!"

frobisher walked briskly down to the place ernest renan and the rue de la liberté, dwelling upon hanaud's injunction to examine the façade of notre dame. he must keep that in mind and obey it in the morning. but that night was not yet over for him.

as he reached the mouth of the little street of charles-robert he heard a light, quick step a little way behind him—a step that seemed familiar. so when he turned into the street he sauntered and looked round. he saw a tall man cross the entrance of the street very quickly and disappear between, the houses on the opposite side. the man paused for a second under the light of a street lamp at the angle of the street, and jim could have sworn that it was hanaud. there were no hotels, no lodgings in this quarter of the city. it was a quarter of private houses. what was hanaud seeking there?

speculating upon this new question, he forgot the façade of notre dame; and upon his arrival at the maison crenelle a little incident occurred which made the probability that he would soon remember it remote. he let himself into the house with a latchkey which had been given to him, and turned on the light in the hall by means of a switch at the side of the door. he crossed the hall to the foot of the stairs, and was about to turn off the light, using the switch there to which ann upcott had referred, when the door of the treasure-room opened. betty appeared in the doorway.

"you are still up?" he said in a low voice, half pleased to find her still afoot and half regretful that she was losing her hours of sleep.

"yes," and slowly her face softened to a smile. "i waited up for my lodger."

she held the door open, and he followed her back into the room.

"let me look at you," she said, and having looked, she added: "jim, something has happened to-night."

jim nodded.

"what?" she asked.

"let it wait till to-morrow, betty!"

betty smiled no longer. the light died out of her dark, haunting eyes. lassitude and distress veiled them.

"something terrible, then?" she said in a whisper.

"yes," and she stretched out a hand to the back of a chair and steadied herself.

"please tell me, now, jim! i shall not sleep to-night unless you do; and oh, i am so tired!"

there was so deep a longing in her voice, so utter a weariness in the pose of her young body that jim could not but yield.

"i'll tell you, betty," he said gently. "hanaud and i went to find jean cladel to-night. we found him dead. he had been murdered—cruelly."

betty moaned and swayed upon her feet. she would have fallen had not jim caught her in his arms.

"betty!" he cried.

betty buried her face upon his shoulder. he could feel the heave of her bosom against his heart.

"it's appalling!" she moaned. "jean cladel! ... no one ever had heard of him till this morning ... and now he's swept into this horror—like the rest of us! oh, where will it end?"

jim placed her in a chair and dropped on his knees beside her.

she was sobbing now, and he tried to lift her face up to his.

"my dear!" he whispered.

but she would not raise her head.

"no," she said in a stifled voice, "no," and she pressed her face deeper into the crook of his shoulder and clung to him with desperate hands.

"betty!" he repeated, "i am so sorry.... but it'll all come right. i'm sure it will. oh, betty!" and whilst he spoke he cursed himself for the banality of his words. why couldn't he find some ideas that were really fine with which to comfort her? something better than these stupid commonplaces of "i am sorry" and "it will all straighten out"? but he couldn't, and it seemed that there was no necessity that he should. for her arms crept round his neck and held him close.