Engineer Richard Mason (Humphrey Bogart) is unhappily married to his hectoring wife, Kathryn (Rose Hobart), and makes no secret that he loves her younger sister, Evelyn (Alexis Smith). Driving home from their anniversary party, Mason crashes the car when the reflection of Evelyn in the rearview mirror distracts him. To convalesce, he plans a trip to the mountains and sends Kathryn ahead. Kathryn dies on the way, but Mason begins to see signs that she is alive.