In the mid-fifties, El Nini lives in the poorest and most forgotten rural Castile (Spain). He is a child with no more knowledge than those provided by nature. El Nini lives with his father in a cave, and with him he devotes himself to the hunting of water rats, the only means of subsistence they know. But when they are tried to deprive them of their roof and their livelihood, violence will erupt uncontrollably.