When Harriet Zapper is hired to find the identity of Karel Duval, and the true heir to the Duval family fortune, a bloody trail of murders leads the Big Zapper from London to the South of France and into a hornet's nest of betrayal and death.

Linda Marlowe
as Harriet Zapper

Alan Lake
as Reynaud Duval

Jason Kemp
as Karel Duval

Tony Theng
as Hock

Edina Ronay
as Guy Champion

Noel Johnson
as Christian Duval

Peter Halliday
as Rabelais

David Robb
as Alex Zendor

William Ridoutt
as Inspector Cook

Graham Ashley
as Barfly