"Don't lie to me!"
"He does not smoke at all," repeated the girl, almost mechanically, and stood confronting him with a defiant air.
"Very well. That is all." The detective turned from the room and left the house.
He did not, however, go very far. It was rapidly becoming dark. He passed down the street until he judged he was out of sight of the house, then slowly retraced his steps upon the other side, until he had reached a point nearly opposite the small iron gateway which served as the servants' entrance to Mr. Stapleton's house. Here, hidden behind a tree, he watched for perhaps half an hour.
At the expiration of this period, he was rewarded by seeing a young man, evidently an under servant, emerge from the gateway. Duvall watched him as he proceeded down the street, then began to follow him.
The young man seemed in no great hurry, and at the junction of the avenue with the Champs Élysées, Duvall accosted him, speaking in French.
"Do you want to earn twenty francs, my friend?" he asked pleasantly.
The boy regarded him with a quizzical smile. "Who does not, Monsieur?" he replied.
"Let me see the note you have in your hand."
The boy drew back suddenly, and made as though to thrust the letter into his pocket. "It is impossible, Monsieur," he began.