
An international criminal arrives in London, and a detective is anxious to pin something on him for some unprovable murders of former lovers. The villain starts to suspect servants and henchmen of being a police spy known as "Number Six".

Ivan Desny
Charles Valentine

Nadja Regin
Nadia Leiven

Michael Goodliffe
Det. Supt. Hallett

Brian Bedford
Jimmy Gale
Joyce Blair
Carol Clyde

Leonard Sachs
Weiland
Maxwell Shaw
Luigi Pirani

Harold Goodwin
Smith

John Welsh
Assistant Commissioner

Barrie Ingham
House Agent

Derrick Sherwin
Det. Sgt. Waters
Malou Pantera
Lotte
Andre Mikhelson
Head Waiter
Josephine Gordon
Mrs. Pirani
Norman Florence
Waiter