"Really, Lord Peter," said the doctor, "I think I ought to know what is best for my patient."

"Doctor," said Wimsey, "this is not a question of your patient. A crime has been committed."

"But there is no mystery."

"There are twenty mysteries. For one thing, when was the window-cleaner here last?"

"The window-cleaner?"

"Who shall fathom the ebony-black enigma of the window-cleaner?" pursued Peter lightly, putting a match to his pipe. "You are quietly in your bath, in a state of more or less innocent nature, when an intrusive head appears at the window, like the ghost of Hamilton Tighe, and a gruff voice, suspended between earth and heaven, says 'Good morning, sir.' Where do window-cleaners go between visits? Do they hibernate, like busy bees? Do they——?"

"Really, Lord Peter," said the doctor, "don't you think you're going a bit beyond the limit?"

"Sorry you feel like that," said Peter, "but I really want to know about the window-cleaner. Look how clear these panes are."

"He came yesterday, if you want to know," said Dr. Hartman, rather stiffly.

"You are sure?"