“The devil!” started M. Paul.  “Where?”

Tignol drew back the double doors of a long window, and pointed out to a balcony running along the front of the hotel.

“There!  Let me tell you first how this floor is arranged.  There are six rooms opening on that balcony.  See here,” and taking a sheet of paper, he made a rough diagram.

[Illustration:  Diagram of floor-plan of rooms.]

“Now, then,” continued Papa Tignol, surveying his handiwork with pride, “I think that is clear.  B, here, is the balcony just outside, and there are the six rooms with windows opening on it.  We are in this room D, and my friend, the little photographer, is in the next room E, peacefully sleeping; but he wasn’t peaceful when he came home to-night and heard me playing that flute, although I played in my best manner, eh, eh!  He stood it for about ten minutes, and then, eh, eh!  It was another case of through the wall, first one boot, bang! then another boot, smash! only there were no holes for the boots to come through.  And then it was profanity!  For a small man he had a great deal of energy, eh, eh! that shrimp photographer!  I called him a shrimp when he came bouncing in here.”

“Well, well?” fretted Coquenil.

“Then we got acquainted.  I apologized and offered him beer, which he likes; then he apologized and told me his troubles.  Poor fellow, I don’t wonder his nerves are unstrung!  He’s in love with a pretty dressmaker who lives in this room C. She is fair but fickle—­he tells me she has made him unhappy by flirting with a medical student who lives in this room G. Just a minute, I’m coming to the point.

“It seems the little photographer has been getting more and more jealous lately.  He was satisfied that his lady love and the medical student used this balcony as a lover’s lane, and he began lying in wait at his window for the medical student to steal past toward the dress-maker’s room.”

“Yes?” urged the detective with growing interest.

“For several nights last week he waited and nothing happened.  But he’s a patient little shrimp, so he waited again Saturday night and—­something did happen.  Saturday night!”

“The night of the murder,” reflected the commissary.

“That’s it.  It was a little after midnight, he says, and suddenly, as he stood waiting and listening, he heard a cautious step coming along the balcony from the direction of the medical student’s room, G. Then he saw a man pass his window, and he was sure it was the medical student.  He stepped out softly and followed him as far as the window of room C. Then, feeling certain his suspicions were justified, he sprang upon the man from behind, intending to chastise him, but he had caught the wrong pig by the ear, for the man turned on him like a flash and—­it wasn’t the medical student.”

“Who was it?  Go on!” exclaimed the others eagerly.

“He doesn’t know who it was, or anything about the man except that his hand shut like a vise on the shrimp’s throat and nearly choked the life out of him.  You can see the nail marks still on the cheek and neck; but he remembers distinctly that the man carried something in his hand.”