Serena

Patrick Holt

Inspector Gregory

Emrys Jones

Howard Rogers

Honor Blackman

Ann Rogers

Bruce Beeby

Det. Sgt Conway

John Horsley

Mr. Fisher

Robert Perceval

Bank Manager

Wally Patch

Barman

Frank Pettitt

Fred

Benedicta Leigh

Policewoman Scott

Peter Glaze

Station Booking Clerk

Vi Stevens

Landlady

Howard Greene

River Police Sergeant

Raymond Smith

River Police Constable

Lawrence James

Uniformed Constable

Reginald Hearne

Doctor (as Reggie Hearne)

Barry Linehan

Forensic Chemist

Gerry Duggan

Norman Cole

Colin Rix

Plain Clothes Detective

Bill Mills

Photographer

Pat Shaw

Uniformed Policewoman

John Tatham

PC Barrow (uncredited)