In the long war of nerves between East and West, British agent David Callan has distinguished himself as a valuable asset: a competent killer who understands all the political and psychological angles. But after a stint in Soviet prison, Callan wants out of the game. His coldly calculating superiors, Hunter (William Squire, Anne of the Thousand Days) and Bishop (Geoffrey Chater, Hotel du Lac), have other ideas. Callan soon learns that leaving his profession might become more dangerous than staying in-and that men like him have as much to fear from friends as from enemies. In these final 13 episodes, this taut series elevates the spy thriller to emotionally charged drama.