"Deathtrap" by Ira Levin

Sidney Bruhl hasn’t written a hit play for 18 years when he receives a script from a former student, Clifford Anderson, that’s a guaranteed success. His wife, Myra, suggests the two men could collaborate; Sidney jokes that it’d be just as easy to murder the young man and steal the script for his own. When Clifford arrives later that evening, no one--not even the visiting psychic--could predict where the dark events of the night will go. Who is innocent? Who only seems that way?