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 tells Alba’s secrets, which surprise everyone. Darío takes his daughter Inés home, near the school, where she has very strange visions. An unexpected postcard from Manuel assuring that he’s all right discredits Amaia’s story about his disappearance. León sneaks into Darío and Inés’ home, the students organize a secret party and Elías and Elvira grow closer.

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.