Once upon a time in the summer season, a group of teenagers called Maria, Julia and Clara, who were accompanied by two friends Luis and Pedro, decide to embark on an adventure, all of them are going to ask permission from their parents except Maria who was an orphan, because her mother died when she was born and her father mysteriously disappeared. After obtaining everyone's permission, they enter the mountains until they find a desolate hut. After a review of the surroundings they agree to camp there.

The night comes and the darkness takes over the place. In the meantime, Pedro and luis take some trunks to light a fire, while the women set up the hut to stay that morning.

Already with the fire burning, Pedro sits gazing at the stars as Luis enters the cabin. in that, a quick movement surprises Pedro, he rises up carefully looking to the sides and tries to warn his companions of the meaning; however, a fierce surprise strikes against him and catches him with its claws. Pedro presents resistance but falls down and is dragged to a remote place, he could only hurt the face of the animal with a lit trunk.

After an hour, Luis goes out with Julia to join Pedro, a silence they feel in the outskirts while they see that some logs are scattered in the place. Julia decides to separate from Luis to look for Pedro and a little scared she starts shouting -Pedro, pedro- where are you? but she doesn't get any answer; suddenly, a flying animal interrupts her and in a single flight she tears off her hair, it was a voracious scream that Julia let go, she falls to the ground of pain, in that the bird attacks her again and pecks at her, She could only take one wing and tear off some feathers but in the end she collapses in blood.

Luis rushes to the place where he hears Julia's scream, but he doesn't find her, he only sees traces of hair and the feathers of some bird, he returns terrified to the hut to take refuge next to Maria and Clara. The sensation of fear overwhelms him and he loses all sanity, his clumsiness leads him to stumble upon a tree root; in that instant, a kind of snake wraps itself around his neck and squeezes him to try to suffocate him, Luis a little disoriented takes out a knife from his pocket and manages to hurt the body of the snake but it surpasses the energy of its prey and succeeds in murdering Luis.

In the cabin, Maria is in the bathroom, and Clara goes quietly in search of her companions to offer her some food that she would have brought to share, when she opens the door, a spider falls on Clara and itches her neck, she unconsciously shakes her hand when she feels the prick and tomb the spider causing a wound in one of her legs, Clara perceives a strange sensation and faints all over the door of the cabin.

Maria goes out and finds Clara lying on the floor, she cries desperately when she sees that she had no vital signs, she runs around the house in search of the others, -Boys, where they are.... -Clara is dead, where are you? Suddenly a huge beast stands in front of her, and without words sees the eyes of that quadruped. Mary recedes slightly, but the strong emotion gave her a heart attack that caused her death instantly. Something strange happened. The beast kneels and begins to groan, a small transformation is suffering, little by little it is becoming human.

One night I went camping with my friends, that night of mischief I killed a wolf and immediately the moon turned red as if mourning the death of that animal, a powerful spirit took over my body and left a curse on me; from that time, the bloody moon gives me the power to transform myself into any animal and I wander with the mission of attacking everyone who hoce visit this place.