"Bon Dieu! What a pity! We can never get a clean print in this mess. But wait! How far along the alleyway did you look?"
"As far as that back wall. Poor Gibelin! He never thought of looking on the other side of it. Eh, eh!"
Coquenil breathed more freely. "We may be all right yet. Ah, yes," he cried, going quickly to this back wall where the alleyway turned to the right along the rear of the hotel. Again he threw his white light before him and, with a start of satisfaction, pointed to the ground. There, clearly marked, was a line of footprints, a single line, with no breaks or imperfections, the plain record on the rain-soaked earth that one person, evidently a man, had passed this way, going out.
"I'll send the dog first," said M. Paul. "Here, Cæsar! Cherche!"
Once more the eager animal sprang forward, following slowly along the row of trees where the trail was confused, and then, at the corner, dashing ahead swiftly, only to stop again after a few yards and stand scratching uneasily at a closed door.
"That settles it," said Coquenil. "He has brought us to the alleyway door. Am I right?"
"Yes," nodded Gritz.
"The door that leads to Number Seven?"
"Yes."
"Open it," and, while the agitated proprietor searched for his pass key, the detective spoke to Tignol: "I want impressions of these footprints, the best you can take. Use glycerin with plaster of Paris for the molds. Take this one and these two and this and this. Understand?"
"Perfectly."
"Leave Cæsar here while you go for what you need. Down, Cæsar! Garde!"
The dog growled and went on guard forthwith.
"Now, we'll have a look inside."
The alleyway door stood open and, using his lantern with the utmost care, Coquenil went first, mounting the stairs slowly, followed by Gritz. At the top they came to a narrow landing and a closed door.
"This opens directly into Number Seven?" asked the detective.
"Yes."
"Is it usually locked or unlocked?"
"IT is always locked."
"Well, it's unlocked now," observed Coquenil, trying the knob. Then, flashing his lantern forward, he threw the door wide open. The room was empty.
"Let me turn up the electrics," said the proprietor, and he did so, showing furnishings like those in Number Six except that here the prevailing tint was pale blue while there it was pale yellow.
"I see nothing wrong," remarked M. Paul, glancing about sharply. "Do you?"
"Nothing."
"Except that this door into the corridor is bolted. It didn't bolt itself, did it?"
"No," sighed the other.
Coquenil thought a moment, then he produced the pistol found in the courtyard and examined it with extreme care, then he unlocked the corridor door and looked out. The policeman was still on guard before Number Six.
"I shall want to go in there shortly," said the detective. The policeman saluted wearily.
"Excuse me," ventured M. Gritz, "have you still much to do?"
"Yes," said the other dryly.
"It's nearly four and—I suppose you are used to this sort of thing, but I'm knocked out, I—I'd like to go to bed."
"By all means, my dear sir. I shall get on all right now if—oh, they tell me you make wonderful Turkish coffee here. Do you suppose I could have some?"
"Of course you can. I'll send it at once."
"You'll earn my lasting gratitude."
Gritz hesitated a moment and then, with an apprehensive look in his beady eyes, he said: "So you're going in there?" and he jerked his fat thumb toward the wall separating them from Number Six.
Coquenil nodded.
"To see if the ball from that," he looked with a shiver at the pistol, "fits in—in that?" Again he jerked his thumb toward the wall, beyond which the body lay.
"No, that is the doctor's business. Mine is more important. Good night!"
"Good night," answered Gritz and he waddled away down the corridor in his blue-silk garments, wagging his heavy head and muttering to himself: "More important than that! Mon Dieu!"
Chapter VIII.
Through the Wall
Coquenil's examination of the pistol showed that it was a weapon of good make and that only a single shot had been fired from it; also that this shot had been fired within a few hours. Which, with the evidence of the seamstress and the dog, gave a strong probability that the instrument of the crime had been found. If the ball in the body corresponded with balls still in the pistol, this probability would become a practical certainty. And yet, the detective knit his brows. Suppose it was established beyond a doubt that this pistol killed the billiard player, there still remained the question how the shooting was accomplished. The murderer was in Number Seven, he could not and did not go into the corridor, for the corridor door was locked. But the billiard player was in Number Six, he was shot in Number Six, and he died in Number Six. How were these two facts to be reconciled? The seamstress's testimony alone might be put aside but not the dog's testimony. The murderer certainly remained in Number Seven.
Holding this conviction, the detective entered the room of the tragedy and turned up the lights, all of them, so that he might see whatever was to be seen. He walked back and forth examining the carpet, examining the walls, examining the furniture, but paying little heed to the body. He went to the open window and looked out, he went to the yellow sofa and sat down, finally he shut off the lights and withdrew softly, closing the door behind him. It was just as the commissary had said with the exception of one thing.
When he returned to Number Seven, M. Paul found that Gritz had kept his promise and sent him a pot of fragrant Turkish coffee, steaming hot, and a box of the choicest Egyptian cigarettes. Ah, that was kind! This was something like it! And, piling up cushions in the sofa corner, Coquenil settled back comfortably to think and dream. This was the time he loved best, these precious silent hours when the city slept and his mind became most active—this was the time when chiefly he received those flashes of inspiration or intuition that had so often and so wonderfully guided him.
For half an hour or so the detective smoked continuously and sipped the powdered delight of Stamboul, his gaze moving about the room in friendly scrutiny as if he would, by patience and good nature, persuade the walls or, chairs to give up their secret. Presently he took off his glasses and, leaning farther back against the cushions, closed his eyes in pleasant meditation. Or was it a brief snatch of sleep? Whichever it was, a discreet knock at the corridor door shortly ended it, and Papa Tignol entered to say that he had finished the footprint molds.
M. Paul roused himself with an effort and, sitting up, his elbow resting against the sofa back, motioned his associate to a chair.
"By the way," he asked, "what do you think of that?" He pointed to a Japanese print in a black frame that hung near the massive sideboard.
"Why," stammered Tignol, "I—I don't think anything of it."
"A rather interesting picture," smiled the other. "I've been studying it."
"A purple sea, a blue moon, and a red fish—it looks crazy to me," muttered the old agent.
Coquenil laughed at this candid judgment. "All the same, it has a bearing on our investigations."
"Diable!"