Secret agent Harry Palmer (Oscar-winner Michael Caine) is blackmailed into working for MI5 again on his wildest - and most dangerous - assignment yet. An insane oil billionaire, intent on destroying Communism by starting a new world war, is close to achieving his goal with the help of the world's largest, and most powerful, computer. Harry is the only man who may be able to stop him; but as he races from London to Finland to Latvia to Texas and back, he must determine who of his supposed allies (a sexy Russian agent, a Soviet colonel and an American mercenary) is the one he can actually trust!