On the eve of the Second World War, David Spaulding, a radio voice actor, is recruited by Colonel Ed Pace to run a secret network in Lisbon.

The German intelligence agency, the Nachrichtendienst, discovers that the Allies are in need of gyroscopes, and proposes an exchange, to take place in neutral territory: Buenos Aires, Argentina.

While he is in New York, awaiting details on his assignment, he encounters an old flame, Leslie Jenner Hawkwood who, having drawn him away from his apartment, seemingly vanishes into thin air.

Upon arrival in Buenos Aires, Spaulding meets and falls in love with Jean Cameron, a woman employed by the embassy.

In 1977 the book was adapted as a five-hour, three-part mini-series, directed by Burt Kennedy, and starring Stephen Collins (as David Spaulding), Lauren Hutton (as Leslie Hawkewood), Vince Edwards (as General Swanson), José Ferrer (as Erich Rhinemann), Larry Hagman (as Colonel Pace), John Huston (as Ambassador Granville), Roddy McDowall (as Bob Ballard), René Auberjonois (as Dr Lyons), Werner Klemperer (as Franz Altmuller), Claude Akins (as Walter Kendall), and Jeremy Kemp (as Geoffrey Moore).