A great detective must have infinite patience. That is, the quality next to imagination that will serve him best. Indeed, without patience, his imagination will serve him but indifferently. Take, for instance, so small a thing as the auger used at the Ansonia. Coquenil felt sure it had been bought for the occasion—billiard players do not have augers conveniently at hand. It was probably a new one, and somewhere in Paris there was a clerk who might remember selling it and might be able to say whether the purchaser was Martinez or some other man. M. Paul believed it was another man. His imagination told him that the person who committed this crime had suggested the manner of it, and overseen the details of it down to even the precise placing of the eye holes. It must be so or the plan would not have succeeded. The assassin, then, was a friend of Martinez—that is, the Spaniard had considered him a friend, and, as it was of the last importance that these holes through the wall be large enough and not too large, this friend might well have seen personally to the purchase of the auger, not leaving it to a rattle-brained billiard player who, doubtless, regarded the whole affair as a joke. It was not a joke!

So, as part of his day's work, M. Paul had taken steps for the finding of this smallish object dropped into the Seine by Pussy Wilmott, and, betimes on the morning after that lady's examination, a diver began work along the Concorde bridge under the guidance of a young detective named Bobet, selected for this duty by M. Paul himself. This was one thread to be followed, a thread that might lead poor Bobet through weary days and nights until, among all the hardware shops in Paris, he had found the particular one where that particular auger had been sold!

Another thread, meanwhile, was leading another trustworthy man in and out among friends of Martinez, whom he must study one by one until the false friend had been discovered. And another thread was hurrying still another man along the trail of the fascinating Anita, for Coquenil wanted to find out why she had changed her mind that night, and what she knew about the key to the alleyway door. Somebody gave that key to the assassin!

Besides all this, and more important, M. Paul had planned a piece of work for Papa Tignol when the old man reported for instructions this same Wednesday morning just as the detective was finishing his chocolate and toast under the trees in the garden.

"Ah, Tignol!" he exclaimed with a buoyant smile. "It's a fine day, all the birds are singing and—we're going to do great things." He rubbed his hands exultantly, "I want you to do a little job at the HÔtel des Étrangers, where Kittredge lived. You are to take a room on the sixth floor, if possible, and spend your time playing the flute."

"Playing the flute?" gasped Tignol. "I don't know how to play the flute."

"All the better! Spend your time learning! There is no one who gets so quickly in touch with his neighbors as a man learning to play the flute."

"Ah!" grinned the other shrewdly. "You're after information from the sixth floor?"

M. Paul nodded and told his assistant exactly what he wanted.

"Eh, eh!" chuckled the old man. "A droll idea! I'll learn to play the flute!"

"Meet me at nine to-night at the Three Wise Men and—good luck. I'm off to the SantÉ."

As he drove to the prison Coquenil thought with absorbed interest of the test he was planning to settle this question of the footprints. He was satisfied, from a study of the plaster casts, that the assassin had limped slightly on his left foot as he escaped through the alleyway. The impressions showed this, the left heel being heavily marked, while the ball of the left foot was much fainter, as if the left ankle movement had been hampered by rheumatism or gout. It was for this reason that Coquenil had been at such pains to learn whether Kittredge suffered from these maladies. It appeared that he did not. Indeed, M. Paul himself remembered the young man's quick, springy step when he left the cab that fatal night to enter Bonneton's house. So now he proposed to make Lloyd walk back and forth several times in a pair of his own boots over soft earth in the prison yard and then show that impressions of these new footprints were different in the pressure marks, and probably in the length of stride, from those left in the alleyway. This would be further indication, along with the differences already noted in the nails, that the alleyway footprints were not made by Kittredge.

Not made by Kittredge, reflected the detective, but by a man wearing Kittredge's boots, a man wearing the missing third pair, the stolen pair! Ah, there was a nut to crack! This man must have stolen the boots, as he had doubtless stolen the pistol, to throw suspicion on an innocent person. No other conclusion was possible; yet, he had not returned the boots to Kittredge's room after the crime. Why not? It was essential to his purpose that they be found in Kittredge's room, he must have intended to return them, something quite unforeseen must have prevented him from doing so. What had prevented the assassin from returning Kittredge's boots?

As soon as Coquenil reached the prison he was shown into the director's private room, and he noticed that M. Dedet received him with a strange mixture of surliness and suspicion.

"What's the trouble?" asked the detective.

"Everything," snarled the other, then he burst out: "What the devil did you mean by sending that girl to me?"

"What did I mean?" repeated Coquenil, puzzled by the jailer's hostility. "Didn't she tell you what she wanted?"

Dedet made no reply, but unlocking a drawer, he searched among some envelopes, and producing a square of faded blotting paper, he opened it before his visitor.

"There!" he said, and with a heavy finger he pointed to a scrawl of words. "There's what she wrote, and you know damned well you put her up to it."

Coquenil studied the words with increasing perplexity. "I have no idea what this means," he declared.

"You lie!" retorted the jailer.

M. Paul sprang to his feet. "Take that back," he ordered with a look of menace, and the rough man grumbled an apology. "Just the same," he muttered, "it's mighty queer how she knew it unless you told her."

"Knew what?"

The jailer eyed Coquenil searchingly. "Nom d'un chien, I guess you're straight, after all, but—how did she come to write that?" He scratched his dull head in mystification.

"I have no idea."

"See here," went on Dedet, almost appealingly, "do you believe a girl I never saw could know a thing about me that nobody knows?"

"Strange!" mused the detective. "Is it an important thing?"

"Is it? If it hadn't been about the most important thing, do you think I'd have broken a prison rule and let her see that man? Well, I guess not. But I was up against it and—I took a chance."

Coquenil thought a moment. "I don't suppose you want to tell me what these words mean that she wrote?"

"No, I don't," said the jailer dryly.

"All right. Anyhow, you see I had nothing to do with it." He paused, and then in a businesslike tone: "Well, I'd better get to work. I want that prisoner out in the courtyard."

"Can't have him."

"No? Here's the judge's order."

But the other shook his head. "I've had later orders, just got 'em over the telephone, saying you're not to see the prisoner."

"What?"

"That's right, and he wants to see you."

"He? Who?"

"The judge. They've called me down, now it's your turn."

Coquenil took off his glasses and rubbed them carefully. Then, without more discussion, he left the prison and drove directly to the Palais de Justice; he was perplexed and indignant, and vaguely anxious. What did this mean? What could it mean?

As he approached the lower arm of the river where it enfolds the old island city, he saw Bobet sauntering along the quay and drew up to speak to him.

"What are you doing here?" he asked. "I told you to watch that diver."

The young detective shrugged his shoulders. "The job's done, he found the auger."

"Ah! Where is it?"

"I gave it to M. Gibelin."

Coquenil could scarcely believe his ears.

"You gave the auger to Gibelin? Why?"

"Because he told me to."

"You must be crazy! Gibelin had nothing to do with this. You take your orders from me."

"Do I?" laughed the other. "M. Gibelin says I take orders from him."

"We'll see about this," muttered M. Paul, and crossing the little bridge, he entered the courtyard of the Palais de Justice and hurried up to the office of Judge Hauteville. On the stairs he met Gibelin, fat and perspiring.

"See here," he said abruptly, "what have you done with that auger?"

"Put it in the department of old iron," rasped the other. "We can't waste time on foolish clews."

Coquenil glared at him. "We can't, eh? I suppose you have decided that?"

"Precisely," retorted Gibelin, his red mustache bristling.

"And you've been giving orders to young Bobet?"

"Yes, sir."

"By what authority?"

"Go in there and you'll find out," sneered the fat man, jerking a derisive thumb toward Hauteville's door.

A moment later M. Paul entered the judge's private room, and the latter, rising from his desk, came forward with a look of genuine friendliness and concern.

"My dear Coquenil," exclaimed Hauteville, with cordial hand extended. "I'm glad to see you but—you must prepare for bad news."

Coquenil eyed him steadily. "I see, they have taken me off this case."

The judge nodded gravely. "Worse than that, they have taken you off the force. Your commission is canceled."

"But—but why?" stammered the other.

"For influencing Dedet to break a rule about a prisoner au secret; as a matter of fact, you were foolish to write that letter."

"I thought the girl might get important evidence from her lover."

"No doubt, but you ought to have asked me for an order. I would have given it to you, and then there would have been no trouble."

"It was late and the matter was urgent. After all you approve of what I did?"

"Yes, but not of the way you did it. Technically you were at fault, and—I'm afraid you will have to suffer."

M. Paul thought a moment.

"Did you make the complaint against me?"

"No, no! Between ourselves, I should have passed the thing over as unimportant, but—well, the order came from higher up."

"You mean the chief revoked my commission?"

"I don't know, I haven't seen the chief, but the order came from his office."

"With this prison affair given as the reason?"

"Yes."

"And now Gibelin is in charge of the case?"

"Yes."

"And I am discharged from the force? Discharged in disgrace?"

"It's a great pity, but——"

"Do you think I'll stand for it? Do you know me so little as that?" cut in the other with increasing heat.

"I don't see what you're going to do," opposed the judge mildly.

"You don't? Then I'll tell you that—" Coquenil checked himself at a sudden thought. "After all, what I do is not important, but I'll tell you what Gibelin will do, and that is important, he will let this American go to trial and be found guilty for want of evidence that would save him."

"Not if I can help it," replied Hauteville, ruffled at this reflection on his judicial guidance of the investigation.

"No offense," said M. Paul, "but this is a case where even as able a judge as yourself must have special assistance and—Gibelin couldn't find the truth in a thousand years. Do you think he's fit to handle this case?"

"Officially I have no opinion," answered Hauteville guardedly, "but I don't mind telling you personally that I—I'm sorry to lose you."

"Thanks," said M. Paul. "I think I'll have a word with the chief."

In the outer office Coquenil learned that M. Simon was just then in conference with one of the other judges and for some minutes he walked slowly up and down the long corridor, smiling bitterly, until presently one of the doors opened and the chief came out followed by a black bearded judge, who was bidding him obsequious farewell.

As M. Simon moved away briskly, his eye fell on the waiting detective, and his genial face clouded.

"Ah, Coquenil," he said, and with a kindly movement he took M. Paul's arm in his. "I want a word with you—over here," and he led the way to a wide window space. "I'm sorry about this business."

"Sorry?" exclaimed M. Paul. "So is Hauteville sorry, but—if you're sorry, why did you let the thing happen?"

"Not so loud," cautioned M. Simon. "My dear fellow, I assure you I couldn't help it, I had nothing to do with it."

Coquenil stared at him incredulously. "Aren't you chief of the detective bureau?"

"Yes," answered the other in a low tone, "but the order came from—from higher up."

"You mean from the prÉfet de police?"

M. Simon laid a warning finger on his lips. "This is in strictest confidence, the order came through his office, but I don't believe the prÉfet issued it personally. It came from higher up!"

"From higher up!" repeated M. Paul, and his thoughts flashed back to that sinister meeting on the Champs ElysÉes, to that harsh voice and flaunting defiance.

"He said he had power, that left-handed devil," muttered the detective, "he said he had the biggest kind of power, and—I guess he has."