To Wake the Dead — John Dickson Carr

A purloined breakfast produced a body in a trunk

The victim of his own bizarre bet, mystery writer Christopher Kent swindled breakfast at London's Royal Scarlet Hotel -- only to find himself frantically trying to flee a darkened suite whose occupant was a savagely murdered young woman.

Enlisting the aid of Dr. Gideon Fell, Chris discovered with horror that the corpse was lovely Jenny Kent. She was the wife of his cousin Rodney who had been murdered in identical fashion two weeks earlier at a country estate miles away. From Piccadilly Circus, portly Dr. Fell and the police follow a gravestone-marked trail to Sussex, and a solution to a pattern of madness spun half a world away.