Mr. Marnstam was thinking. “Do you remember that sound through the darkness,” he said--“the beating of an engine way back on the road?” “What of it?” Rounceby demanded. “It was a motor bicycle,” Marnstam said quietly. “I thought so at the time.” “Supposing some one followed us and pulled him out,” Rounceby said, hoarsely, “why are we treated like this? I tell you we’ve been made fools of! We’ve been treated like children--not even to be punished! We’ll have the truth somehow out of that devil Cawdor! Come!” They made their way to the courtyard and found a cab. “Number 27, Southampton Row!” they ordered. They reached their destination some time before Dory, whose horse fell down in the Strand, and who had to walk. They ascended to the fourth floor of the building and rang the bell of Vincent Cawdor’s room--no answer. They plied the knocker--no result. Rounceby peered through the keyhole. “He hasn’t come home yet,” he remarked. “There is no light anywhere in the place.” The door of a flat across the passage was quietly opened. Mr. Peter Ruff, in a neat black smoking suit and slippers, and holding a pipe in his hand, looked out. “Excuse me, gentlemen,” he said, “but I do not think that Mr. Cawdor is in. He went out early this evening, and I have not heard him return.” The two men turned away. “We are much obliged to you, sir,” Mr. Marnstam said. “Can I give him any message?” Peter Ruff asked, politely. “We generally see something of one another in the morning.” “You can tell him--” Rounceby began. “No message, thanks!” Marnstam interrupted. “We shall probably run across him ourselves to-morrow.” John Dory was nearly a quarter of an hour late. After his third useless summons, Mr. Peter Ruff presented himself again. “I am afraid,” he said, “you will not find my neighbour at home. There have been several people enquiring for him to-night, without any result.” John Dory came slowly across the landing. “Good evening, Mr. Ruff!” he said. “Why, it’s Mr. Dory!” Peter Ruff declared. “Come in, do, and have a drink.” John Dory accepted the invitation, and his eyes were busy in that little sitting room during the few minutes which it took his host to mix that whisky and soda. “Nothing wrong with our friend opposite, I hope?” Peter Ruff asked, jerking his head across the landing. “I hope not, Mr. Ruff,” John Dory said. “No doubt in the morning he will be able to explain everything. I must say that I should like to see him to-night, though.” “He may turn up yet,” Peter Ruff remarked, cheerfully. “He’s like myself--a late bird.” “I fear not,” Dory answered, drily. “Nice rooms you have here, sir. Just a sitting room and bedroom, eh?” Peter Ruff stood up and threw open the door of the inner apartment. “That’s so,” he answered. “Care to have a look round?” The detective did look round, and pretty thoroughly. As soon as he was sure that there was no one concealed upon the premises, he drank his whisky and soda and went.