When twelve children disappear from Lake Como during the summer school holidays, the police chief is baffled. There are no clues and no witnesses, even though the camping grounds are overflowing with holidaymakers and the children disappear in broad daylight. The children have been cast into a spell to live as spirits in the river Kai, divided into two opposing groups: the river spirits and the wood spirits. The river spirits can escape the spell and return home as children, but only with dire consequences for the wood spirits. The children learn that it is only through trust, camaraderie, and teamwork do they have a chance to return home to their families, however, when a wood spirit named Faith, turns into a mass of bubbles and floats away down the river Kai, all bets are off, even though a greater threat emerges on the banks of the river Kai.