Marc, a motorcycle brigadier, is engaged to the charming Véronique. But his future brother-in-law, the clumsy Roger, leader of a Sunday motorcycle gang, has set his sights on joining the motorcycle police.

On the run from international police, Special Agent Lemmy Caution arrives in the South of France and soon becomes embroiled in a scheme with the infamous gangster Siegella. Whilst seeming to co-operate with the underworld boss, Lemmy is secretly acting for the FBI, and intends using Miranda Van Zelden, a wealthy heiress, as bait to trap a gang of crooks and put an end to Siegella's exploits...

Albert is an eccentric inventor of missiles who comes under fire from his investors when his first prototype explodes. Even his sympathetic mistress has her doubts, as Albert lashes out in a verbal tirade condemning those of little faith in his genius.