TOMMY HEAD is a charming but clueless civil servant whose steady rise through the ranks of the civil service has been propelled by the recommendations of a succession of exasperated line managers because that's the only way they can get rid of him. When his latest posting requires Tommy to pass a positive vetting process, a colleague warns him he will fail if there's any suspicion about his sexuality. Tommy rashly claims eighty sexual encounters rather than admit to a longstanding affair with his godfather's wife, Priscilla. Bert Pooter, the ex-policeman in charge of the investigation, is consumed with jealousy, but his damning report is rejected. He vows to take revenge after a humiliating visit to a city chemist's shop.
Tommy takes up his job with a local authority, and discovers that his new boss, Colin Tucker (Major Ret'd), is a narcissistic fitness fanatic. He nominates Tommy to take his place as a keynote speaker at a secretive emergency planning facility in Cheshire. Tommy has no idea what to say, but is saved from disaster when his presentation is cancelled after a failed sabotage attempt by Bert Pooter, leaving Tommy with his reputation enhanced.
Tucker subsequently takes Tommy on a Territorial Army exercise, but is outraged when Tommy proves a crack shot, and becomes convinced that Tommy is after his job. To get rid of Tommy he arranges his transfer to the department for civil contingencies where Tommy is approached by a film director from the Central Office of Information asking him to star in a training video. But it turns out that the director has a very different project in mind. When the unwitting Tommy agrees to attend a so-called fund-raising evening, he finds himself at the centre of a sex orgy, and is astonished to recognise two senior politicians and a bishop. Bert Pooter has been stalking him, and tips off a gossip magazine, saying Tommy was the event's chief organiser.
Tommy engages a minor villain to make Pooter withdraw his accusation, but the story still gets out and in the resulting media furore the government is rocked with resignations. Tommy's boss decides he is a liability, and recommends him to a leading marketing consultancy who send him to El Salvador and Panama to sell British tasers to their military dictatorships.
In San Salvador Tommy narrowly avoids getting blown up by a land mine before going on to Panama where he gets caught up in the American invasion of Panama to oust General Noriega. In Panama City he meets Julia, a British diplomat, and romance beckons. On his return to the UK he joins a think tank specialising in El Salvador affairs and helps prepare a report on its political future. The report is praised by his firm's American partner, and Tommy is reunited with Julia who has been transferred to the British embassy in Washington. They subsequently marry at a slap-up wedding where Bert Pooter makes a final, unsuccessful attempt to get even.