The Door in the Floor.

The lives of Ted and Marion Cole are thrown into disarray when their two adolescent sons die in a car wreck. Marion withdraws from Ted and Ruth, the couple's daughter. Ted, a well-known writer, hires as his assistant a student named Eddie, who looks oddly similar to one of the Coles' dead sons. The couple separate, and Marion begins an affair with Eddie, while Ted has a dalliance with his neighbor Evelyn.