A man witnesses a murder in a secluded mansion. When he reports it, there's no evidence of the murder, or that anyone was there. Two years later he wakes up in a hospital room after a polo accident to find he's had amnesia, is now married, and living in Switzerland. Now remembering the incident he returns to England to try to solve the mystery.
| Actor | Role |
|---|---|
 Louis JourdanRichard Stuart | Richard Stuart |
 Mary Tyler MooreElizabeth Sutton | Elizabeth Sutton |
 Wilfrid Hyde-WhiteDr. Ralph Sawyer | Dr. Ralph Sawyer |
 Stanley HollowayCaretaker | Caretaker |
 Alexander KnoxSir Howard Nettleton | Sir Howard Nettleton |
 Terence AlexanderPeter Martin | Peter Martin |
 Ronald HowardInsp. Huntington | Insp. Huntington |
 Laurence NaismithLord Dunnsfield | Lord Dunnsfield |
 Norman BirdSgt. Hooper | Sgt. Hooper |
 Ernest ClarkChairman | Chairman |
 Bernard ArchardBusiness Spokesman | Business Spokesman |
 Nora NicholsonMiss Abernathy | Miss Abernathy |
 Jean AndersonSister Teresa | Sister Teresa |
| EElspeth MarchMrs. Doyle | Mrs. Doyle |
| GGeoffrey CheshireNavvy | Navvy |
 Hilary PritchardPeter Martin's Secretary | Peter Martin's Secretary |
| HHugo de VernierCharles | Charles |
 Norma WestNurse | Nurse |
 Arnold DiamondSwiss News Agent | Swiss News Agent |
| TTimothy KendrickRoger | Roger |
| WWilliam BurleighBrandon | Brandon |
| GGeoffrey FrederickPoliceman in Richard's Flat | Policeman in Richard's Flat |
 Yutte StensgaardGirl At Party | Girl At Party |