Manuel has just returned from a trip that has taken him all over the world with the objective of pointing out the bad state of the world's rivers. The experience has so saddened him that his family, friends and Fast determine that it is necessary that he again learn how to enjoy nature. With that goal, they all go to the natural preserve Alcornales. Their stay in that fantastic scenery and in the baths of Guadiaro river seem idyllic, but the evil Mallory is not willing to leave them be.