Nerea is a girl who lives with her mother in a city where she hasn't made many friends yet. In order for Nerea to meet people her age and get out of her four walls, her mother convinces her to go with a group of young neighbors to spend a weekend in the Sierra. Some members of the group do not like this and Nerea will not have it easy to make friends. When they approach the farmhouse they have rented, they begin to discover strange things. Would it have anything to do with an old Altar they find in a nearby cave? They soon realize that they have gotten into an adventure that will not be easy to survive.