Ingrid Bergman plays Dr. Peterson, a detached and brilliant psychiatrist who falls helplessly in love with Dr. Edwards, played by Gregory Peck, only to find he is an amnesiac and imposter suspected of murdering the true Dr. Edwards. She sets out to prove his innocence, becoming a fugitive herself. Through skilful detective work, she manages to access the dark and confused chambers of his mind finding the clues which help her unravel this perplexing mystery.