The murder is as impossible as it is horrible. Archeologist Reuben Hayles, following written threats to his life, receives police protection at his home. Superintendent Budd stations himself outside the door of his bedroom, while Sergeant Leek remains on alert outside the room's only external window. Yet Hayles is found dead, his head battered by some tremendous blow. Apart from his corpse, the room is empty, devoid of any possible weapon. A search reveals no hidden panels, so how has the...