Two kids call Tom as strange things happen in the castle their father wants to buy from a countess: A pony breathes fire, and the White Lady, a ghost the countess fears, seems to haunt the place.
A princess asks Tom Turbo to investigate the strange behavior of her parents. To do so, his friend Daniel, who is the doppelgänger of the prince, switches places with him.
When Tom Turbo investigates the rumor of a swamp monster, it turns out to be the villain Frettchen. Frettchen begs Tom to go to a mysterious druid's castle and open a door with a lock made of dinosaur heads.