Las Cumbres Boarding School is an impenetrable fortress built on the edge of a cliff where students are subjected to strict discipline and it seems impossible to escape. Two of them manage to run into the woods one night, but things take a turn for the worse because surviving outside the school is even more dangerous than inside and the woods are much more terrifying.

Amaia is lost in the woods when she’s found and taken back to the school where she becomes obsessed with convincing Paul and his friends of what she saw and reporting it. But students at the school are cut off from the outside world. In the library, they find drawings of men wearing bird-like masks that confirm Amaia’s story, but something terrible shocks them all.

Adéle blames Amaia for the party and she’s accused of tattling. Paul and Amaia take Paz and Eric to see a mysterious painting with crow-men, but they find something terrifying instead. Inés undergoes treatment and takes pills that give her hallucinations. Elías and Elvira feel an increasingly irresistible attraction and Paul and Amaia will discover something about Las Cumbres.

The Las Cumbres prior believes the devil runs rampant in the monastery. Amaia discovers a supernatural tie between her and Inés. Elías feels extremely guilty after what happened with Elvira. Meanwhile, Paul finds something in his cell that makes him suspect the friar. Eric suffers a strange blackout and Paul and Amaia follow a clue to find the Crow’s Nest.

One student dead, another student missing, and the kids get framed when the headmaster's search turns up ecstasy among their possessions.

The friends mourn Manuel. The prior discovers Elías has broken his vow of chastity and sends him to another monastery. Meanwhile, Elvira tries to share everything she knows and Inés starts putting pieces about her past together. But a new and unexpected death enrages the students, who start a rebellion at the school. Everything is out of control and we’re in for an unexpected ending.