Patrick Holt as Inspector Gregory

Emrys Jones as Howard Rogers

Honor Blackman as Ann Rogers

Bruce Beeby as Det. Sgt Conway

John Horsley as Mr. Fisher

Robert Perceval as Bank Manager

Wally Patch as Barman

Frank Pettitt as Fred (as Frank Pettit)

Benedicta Leigh as Policewoman Scott

Peter Glaze as Station Booking Clerk

Vi Stevens as Landlady

Howard Greene as River Police Sergeant

Raymond Smith as River Police Constable

Lawrence James as Uniformed Constable

Reginald Hearne as Doctor (as Reggie Hearne)

Barry Linehan as Forensic Chemist

Gerry Duggan as Norman Cole

Colin Rix as Plain Clothes Detective

Bill Mills as Photographer

Pat Shaw as Uniformed Policewoman

John Tatham as PC Barrow (uncredited)