Four kids get lost in the forest in the middle of a storm and go take refuge in an abandoned castle. There they will meet and face Dracula, the Werewolf, Quasimodo and Doctor Frankenstein. Despite the attempts of the monsters to scare them and, in passing, recover their lost prestige, the children, with the help of Count Dracula's son, will face the evil creatures.

One day, without knowing how or why, the birds of a big city leave, disappear. It is believed to be a protest against environmental pollution. Some children (the Regaliz group), then embark on an ecological campaign to get the birds to return to the city.