While driving with one of his gendarmes, Cruchot (Louis de Funès) has to stop in order to fix the car.

The alien begins coughing and upon hitting it on the back, Cruchot discovers it makes a metallic sound.

During the check up, Cruchot notices the same watch on the supervisor as on the alien he saw last night and attempts to attack him.

Cruchot hides at a church while the gendarmes search for him and eventually manages to evade them.

He then attempts to track down the aliens, which proves to be difficult as they can only be identified by the metallic sound they make when struck.

Some of the gendarmes who were searching for him happen to witness this encounter and now believe Cruchot and agree to help him find the aliens.

The chief, who regularly dines at the restaurant, arrives to find it has vanished due to one of the aliens disintegrating it.

The chief brings the remains of the robot to Cruchot and the gendarmes who deduce that water causes the metallic aliens to rust.

They then use a fire truck to spray the citizens of Saint-Tropez with water, hoping to cause damage to any aliens in disguise.

The next day, the gendarmes are being saluted as heroes at a parade, when they suddenly start making metallic noises and collapse.