Two clumsy French thieves, Anatole and Arthur, plan a spectacular heist : the attack of a freight train which carries from Paris to Brussels the secret funds of NATO. They don't know that another team is planning the same attack, the same one which performed the Glasgow-London Great Train Robbery; the team is headed by "The Brain" (David Niven), a British criminal mastermind whose massive brain is so heavy that, when he has a strong emotion, he cannot keep his head upright. The Brain has also a deal with the Sicilian mafia.
Source : Wikipedia
