During one of her regular trips to the lake, Irene meets Nereia, the mysterious daughter of the engineer who rebuilt the dam. For some strange reason, her father keeps her isolated in the residence he built on the banks of the lake, so she has never been able to interact with other people. In an attempt to give her back the youth she has been denied, Irene invites Nereia to join her group of friends. It will be then when they discover that playing with the unknown can have a very high price.