She perceived that the lock was a perfectly ordinary one which probably could be easily unlocked by the key of one of the other doors. Alfred, rather troubled, was sent to collect likely specimens. The fourth that Bundle tried fitted. She turned it, opened the door and passed through.

She found herself in a small, dingy apartment. A long table occupied the centre of the room with chairs ranged round it. There was no other furniture in the room. Two built-in cupboards stood on either side of the fireplace. Alfred indicated the nearer one with a nod.

“That’s it,” he explained.

Bundle tried the cupboard door, but it was locked, and she saw at once that this lock was a very different affair. It was of the patent kind that would only yield to its own key.

“ ’Ighly ingenious, it is,” explained Alfred. “It looks all right when opened. Shelves, you know, with a few ledgers and that on ’em. Nobody’d ever suspect, but you touch the right spot and the whole thing swings open.”