He appeared in the disaster films "Airport 1975" as the co-pilot, and "The Hindenburg" as a sadistic SS captain. Thinnes was cast in Alfred Hitchcock's 1976 film "Family Plot" in the role of nefarious jeweler Arthur Adamson when Hitchcock's first choice, William Devane, was unavailable. Thinnes had already shot several scenes for the film when Devane suddenly became available. Hitchcock fired Thinnes and re-shot all of his scenes. He confronted Hitchcock in a restaurant and asked the director why he was fired. Flabbergasted, Hitchcock simply looked at Thinnes until the actor left. Some shots of Thinnes as the character (from behind) remain in the film.