Whenever a criminal is killed in London, a black Jaguar is nearby, with a white cat always sitting in the passenger seat. Inspector Higgins and Inspector Lane find a joker card on all the victims. Their investigation leads them to a diamond smuggling ring.
Chiefinspector Higgins
Inspector Barbara Lane
Sir John
Flatter
Lady Smith
Mr. Goldman
Mrs. Goldman
Tony Miller
J. Carpenter
Eugene Phipps
Ann Pattison
Reynolds