"Any light behind the shutters?"
"No, sergeant."
Then Paul marched ahead and, while the others, in obedience to his instructions, followed him without making the least noise, he stepped on resolutely, like a belated wayfarer making for home.
They stopped at a narrow-fronted house, the ground-floor of which was hardly distinguishable in the darkness of the night. Three steps led to the door. Paul gave four sharp taps and, at the same time, took a key from his pocket and opened the door.
He switched on his electric lamp again in the passage and, while his companions continued as silent as before, turned to a mirror which rose straight from the flagged floor. He gave four little taps on the mirror and then pushed it, pressing one side of it. It masked the aperture of a staircase which led to the basement; and Paul sent the light of his lantern down the well.
This appeared to be a signal, the third signal agreed upon, for a voice from below, a woman's voice, but hoarse and rasping in its tones, asked:
"Is that you, Daddy Walter?"
The moment had come to act. Without answering, Paul rushed down the stairs, taking four steps at a time. He reached the bottom just as a massive door was closing, almost barring his access to the cellar.
He gave a strong push and entered.
The Comtesse Hermine was there, in the semi-darkness, motionless, hesitating what to do.