Clément keeps the surface dazzling while menace hums below. Decaë shoots blue seas, razor-crease suits and airy interiors so crisp you miss the knife. Delon’s Ripley moves with feline poise; Ronet’s louche playboy spots the teeth too late. A few slack spells stop it from greatness, yet beside the glossy remakes this stays cooler, leaner and more unsettling. If Ripley ever needed a passport mugshot, this would be it.

School friend “Tom” (Alain Delon) has been despatched from the USA to Italy to fetch back the profligate son of a multi-millionaire. “Philip” (Maurice Ronet), however, is perfectly happy swanning around with his girlfriend “Marge” (Marie Laforêt) and so has little intention of returning to San Francisco with his "friend" whom he quite clearly doesn’t really remember. For the moment, “Tom” is quite happy playing the…