(No spoilers)

Sergeant Harry Palmer has been blackmailed into British intelligence after being caught scamming the Army. Trapped carrying out boring surveillance, and treated like a troublesome schoolboy, he passes the time with a mixture of girls, sarcasm and gourmet cooking.

Things start looking up when he is transferred to counter-espionage to investigate the recent disappearance of several top government scientists. However, promotion brings added risk; Palmer suddenly finds himself caught up in the spy's friendless world of paranoia, treachery, brainwashing and assassination.