Caught black-marketeering in Berlin, Harry Palmer faces eight years in a military prison, unless the mysterious Major Dalby can find a use for his skills.
Under the diligent eyes of agent Jean, Palmer's intuition edges them closer to the professor while gun-for-hire former MI6 man Randall is always one step ahead.
Harry and Jean arrive in Beirut in hot pursuit of Randall, who is holding Professor Dawson. Meanwhile, Dalby holds a secret rendezvous with Stok, a Russian colonel.
Dalby challenges General Cathcart, suspecting American involvement in Dawson's abduction. Harry and Jean head to the Pacific atoll where the neutron bomb is to be tested.
Harry is handed over to the Chinese military where he is subjected to a bewildering regime of mental torture. Dalby's love for Dr Lavotchkin takes its toll on his judgement.
