Mason said, “Don’t you see, Mrs. Gentrie? Steele got this room for a purpose. He must have made a habit of opening this door at night after you folks had retired, quietly sneaking down the cellar stairs, going through the garage door, and across to the flat next door. If he didn’t go inside the flat, he at least snooped around the windows and got a line on what was going on inside the place.”
“Why... why, I can’t believe it.”
“And,” Mason went on, with a significant glance at Della Street, “he’s very apt to be over there right now.”
“But why should he want to spy on the people over there?”
Mason said, “He’s evidently in the employ of some Japanese. I understand Lieutenant Tragg thinks some of the people over in that flat could tell something about the smuggling of arms into China.”
“You mean Mr. Hocksley?”
Mason said, “There’s evidence indicating that Hocksley has been engaged in Chinese gun-running for years.”
“Well, good heavens!”
“And Steele evidently secured this room because it gave him such an excellent opportunity to keep an eye on what was going on next door.”
“Well, I’ll declare! Why, then he must have been — he must — why, Mr. Mason, that would make him...”