This comedy sees Will Hay playing a seedy lawyer, who finds himself marked for assassination by a forger whom he previously defended unsuccessfully. He teams up with an incompetent solicitor to try to prevent the deaths of others involved.
The film climaxes with a sequence where Hay hangs from the hands of the clock face of Big Ben in an attempt to prevent a time bomb being detonated.
Employee John David Welles attempts to steal rocket booster plans from the Groundstar facility. His attempt goes awry and he is badly disfigured in an explosion and barely escapes. He stumbles to the home of Nicole Devon, and collapses. She calls an ambulance, the authorities are alerted, and soon Welles is operated on, given plastic surgery and interrogated by a hard-boiled government official named Tuxan. But Welles claims to have no memory of his crime. In fact, he claims no memory of his life at all, save for brief glimpses of a woman and small boy frolicking on a beach.
Despite Tuxan's brutal interrogation techniques (electro-shock and water submersion), Welles still maintains his story of total amnesia. Tuxan allows Welles to escape, hoping he will lead them to the people behind the attempted theft. Welles goes to Nicole's home and begs her to help him remember. But she knows nothing.
Eventually the inside conspirators behind the attempted theft are found, and Tuxan reveals the truth to Welles, who still cannot remember any details of the crime. John David Welles actually died en route to the hospital on the night of the explosion. The man we have come to know as Welles is really Peter Bellamy, a government employee who recently lost his wife and son in an accident. Bellamy, feeling that life was no longer worth living or remembering, volunteered to have his memory wiped and to play Welles in order to draw the conspirators into the open.
