George Peppard as Reno Davis

Inger Stevens as Anne de Villemont

Orson Welles as Leschenhaut

Perrette Pradier as Jeanne-Marie

Keith Michell as Morillon

Geneviève Cluny as Veronique

Maxine Audley as Mathilde Rosier

Ralph Michael as Claude de Gonde

Barnaby Shaw as Paul

Jacques Roux as Maguy

Patience Collier as Goonelle

William Job as Bourdon

Ave Ninchi as Signora Orragi

Renzo Palmer as Monk

Peter Bayliss as Edmond Rosier

Francesco Mulè as Policeman at Trevi Fountain

Rosemary Dexter as Daniela

Raoul Delfosse as Louis Le Buc

James Mishler as Jesse Hardee

Jean Louis as Driot

Jean Hébey as Man in charge of sleeping cars

Jacques Stany as Georges - the family chauffeur

Paule Albert as Sophie

Calisto Calisti as Police Inspector at Rome Station (uncredited)

Andrea Esterhazy as de Villemont Party Guest (uncredited)