In this spy thriller, Robert Vaughn, who then starring on TV's The Man from U.N.C.L.E., plays Bill Fenner, an ex-CIA agent who is called upon by his former boss, Frank Rosenfeld (Ed Asner), to investigate an apparent murder-suicide in Vienna. An American diplomat exploded a bomb at a peace conference, killing himself and all the attendees. Rosenfeld fired Fenner because his wife, Sandra Fane (Elke Sommer), was unmasked as a Communist. Now Rosenfeld tells Fenner that his wife may have been involved with Soviet agents behind the Vienna incident. Fenner eventually finds Sandra, who is hiding from the real bombing culprit, Robert Wahl (Karl Boehm). The story was based on a novel by Helen MacInnes.