It requires patience to get into this film, but once it gets to the central robbery sequence, it becomes genuinely entertaining. James Mason, as "Calvert," is clearly a criminal—a refined one, certainly, but still a crook. He has two sons who seem constantly let down by him: "Stefane" (James Fox) and "Antony" (John Alderton). Dissatisfied with their father’s perpetual disapproval, they enlist the aid of a friend, "Segolene" (Susannah York), and someone capable of pulling off a robbery at sea—"Duffy" (James Coburn). They devise and carry out a remarkably detailed theft involving disguises like wigs, impersonating a priest, and even using a helicopter. The question is whether they’ll succeed. Mason appears infrequently, but for once, Susannah York performs well as their unreliable ally. John Alderton delivers an unexpected performance; I've always associated him with someone similar to a less intense version of John Cleese, yet here he proves quite capable as the mastermind behind the scheme, allowing Coburn to supply both strength and charm. The conclusion felt somewhat convoluted and clumsy, like it was searching for something it couldn’t find, but overall, the film exceeded my expectations, especially the central portion that I found enjoyable.

Source on TMDB