Diablo the giant otter lives in a lake in the jungles of Peru, with his unruly family of six cubs. Even at the tender age of six months, they need to learn how to survive in this dangerous paradise. Their dad teaches them to swim and eventually to catch piranha for themselves, but they must also learn to stay away from the neighbours from hell - the giant caiman. These large members of the crocodile family are a real threat to the giant otter family and Diablo must go to extraordinary lengths to try to protect his cubs.