Hanaud stopped dead and gazed in steady admiration at his junior colleague.
"Oh!" he whispered. "You have discovered that? Yes, it is true. We are being followed by one of my men who sees to it that we are not followed."
Frobisher shook Hanaud's arm off indignantly. He drew himself up stiffly. Then he saw Hanaud's mouth twitching and he understood that he was looking "proper."
"Oh, let us go and find Jean Cladel," he said with a laugh and he crossed the road. They passed into a network of small, mean streets. There was not a soul abroad. The houses were shrouded in darkness. The only sounds they heard were the clatter of their own footsteps on the pavement and the fainter noise of the man who followed them. Hanaud turned to the left into a short passage and stopped before a little house with a shuttered shop front.
"This is the place," he said in a low voice and he pressed the button in the pillar of the door. The bell rang with a shrill sharp whirr just the other side of the panels.
"We may have to wait a moment if he has gone to bed," said Hanaud, "since he has no servant in the house."
A minute or two passed. The clocks struck the half hour. Hanaud leaned his ear against the panels of the door. He could not hear one sound within the house. He rang again; and after a few seconds shutters were thrown back and a window opened on the floor above. From behind the window some one whispered:
"Who is there?"
"The police," Hanaud answered, and at the window above there was silence.
"No one is going to do you any harm," Hanaud continued, raising his voice impatiently. "We want some information from you. That's all."