Written by horror-film specialist Jimmy Sangster, Spy Killer stars Robert Horton as a secret agent turned private eye. Framed for murder, Horton is released, but only after promising that he'll track down a book containing a list of government agents who are operating covertly in Red China. The reluctant spy discovers that he can't completely trust anyone in this endeavor--not even his former chief (Sebastian Cabot). Spy Killer was produced for American television by Britain's Hammer Films, then released theatrically overseas. The film spawned a sequel, Foreign Exchange (70), once again starring Robert Horton and Sebastian Cabot, with Jill St. John reprising her heroine role from Spy Killer.