The door was not locked, and we entered. The room, which was a large double one, was unoccupied. Dust lay about rather noticeably, and my sensitive friend gave a characteristic grimace as he ran his finger round a rectangular mark on a table near the window.

“The service leaves to be desired,” he observed dryly.

He was staring thoughtfully out of the window, and seemed to have fallen into a brown study.

“Well?” I demanded impatiently. “What did we come in here for?”

He started.

“ Je vous demande pardon, mon ami. I wished to see if the door was really bolted on this side also.”