The Man Who Slept All Day — Craig Rice

A weekend getaway among friends becomes an occasion for murder in this “entertaining tantalizer” of a whodunit (Kirkus Reviews).
 
Eccentric brothers Frank and George Faulkner are hosting a weekend house party at the legendary Ravensmoor estate. The guests include a pair of struggling newlyweds, a brutal criminal attorney, a fading chorus girl, and a freeloading couple who live off the fat of their friends. All of them are acquaintances save for a mousy stranger who's more shadow than man.
 
Then, one by one, each visitor makes the same startling discovery: George's corpse snuggled under the covers of his bed. It could've been another of his tasteless practical jokes -- if not for the gaping wound in his neck. Why everyone's been assembled to partake in a murder is only the first mystery. Because the party at Ravensmoor is just getting started . . .