A London solicitor and a French detective investigate the mysterious death of an elderly woman suspected of being poisoned.

Oskar Homolka
as Inspector Hanaud

Robert Urquhart
as Jim Frobisher

Yvonne Furneaux
as Betty Harlowe

Josephine Griffin
as Ann Upcott

Harold Kasket
as Boris Wabersky

Ruth Lodge
as Nurse

Pierre Lefevre
as Detective Maurice Thevenet

Pierre Chaminade
as Detective Moreau

Jacques Cey
as Police Commissaire Giradot

Anthony Nicholls
as Lawyer Jarrett