A year after Sheila is killed in a hit-and-run, her multimillionaire husband invites a group of friends to spend a week on his yacht playing a scavenger hunt-style mystery game—but the game turns out to be all too real and all too deadly.
| Actor | Role |
|---|---|
 Richard BenjaminTom Parkman | Tom Parkman |
 Dyan CannonChristine | Christine |
 James CoburnClinton Greene | Clinton Greene |
 Joan HackettLee Parkman | Lee Parkman |
 James MasonPhilip Dexter | Philip Dexter |
 Ian McShaneAnthony Wood | Anthony Wood |
 Raquel WelchAlice Wood | Alice Wood |
 Yvonne RomainSheila Greene (as Yvonne Romaine) | Sheila Greene (as Yvonne Romaine) |
| PPierre RossoVittorio | Vittorio |
| SSerge CitonGuido | Guido |
| RRoberto RossiCaptain | Captain |
| EElaine GeisingerAmerican Woman | American Woman |
| EElliot GeisingerAmerican Man | American Man |
| JJack PugeatSilver Salesman | Silver Salesman |
| MMaurice CrosnierConcierge (uncredited) | Concierge (uncredited) |
| MMartialLocksmith (uncredited) | Locksmith (uncredited) |