While traveling with his nephews, Donald is disgusted that they are only interested in comics. He stops at the "fountain of youth" and tricks the kids into thinking he is a baby again.
After being framed for a murder he didn't commit, Tom Penney (Donald Houston) serves his time and returns to his rural English home to establish a quiet life.
The residents of a small town are excited when a flaming meteor lands in the hills, until they discover it is the first of many transport devices from Mars bringing an army of invaders invincible to any man-made weapon, even the atomic bomb.
While Ludovic Dubois, a young summer camp monitor in Saint-Benoît, entertains the children by playing Robin Hood, the lord's niece is kidnapped by her uncle, in the castle next door.