In Cider for the Stars, while en route to Champignac, Spirou and Fantasio are confronted with strange events: the villagers see extraterrestrials and animals panic.

When they arrive at the castle, the Count tells them that he is, in fact, housing three extraterrestrials ("Ksoriens"), enrolled in a mycology training program, but that their love for cider had led them to become careless.

One of them is wounded in the town and manages to regain the castle, but its saucer is stolen by foreign secret agents.

In the nick of time Spirou and Fantasio find the saucer and the Ksorien, and the extraterrestrials capture the secret agents.

The Mayor, as is his wont, suspects that the Count is conducting secret experiments and orders the castle to be searched, forcing the Ksoriens to leave.