Les Visiteurs is about the disappearance of a team of six extraterrestrials coming to study Earth. The Empire of the Four Planets dispatch two police detectives to find them. They slip into two human bodies just as they are about to die, those of a Frenchman Jean-Louis and a German woman Renate, and resuscitate them so as to pursue their mission.

Deux visiteurs venus d’un autre univers arrivent sur terre et y prennent forme humaine. Leur mission : retrouver les six membres d’une expédition scientifique précédente, disparus mystérieusement sans laisser de traces.