"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."