Publisher's Synopsis
Could two young women look through a slide in a door and see a girl being murdered - and yet find the room beyond completely empty when they come to enter it with the police? Dr Hiram Carruthers, the famous back-room physicist and investigator, together with Chief Inspector Garth of Scotland Yard, sets out on a tortuous trail. Though the mystery of the killer's identity is not for long in doubt, the method used is a puzzle - until the cynical master-scientist Carruthers fits the pieces into place.
