Marcos y Paula, dos hermanos gallegos cuyos padres han desaparecido en alta mar, ingresan en el internado Laguna Negra bajo la tutela de su director, Héctor de la Vega. Allí, pronto empezarán a suceder extraños acontecimientos y macabras muertes y parece que Paula, de apenas 6 años, está en el centro de todo cuanto pasa a su alrededor: un ser extraño que vaga por el bosque; personajes que no son quienes dicen ser o que saben más de lo que parece; desapariciones; animales mutantes; unos oscuros pasadizos donde se esconden la verdad, muertes, cadáveres y la aparición de la madre de Marcos y Paula. No solo se centra en esta parte, también hay muchas más historias dentro del Internado.
El internado (Temporada 1)

Monsters don't tickle. (Episodio 1) 5.3
Guionista: Ruth García
Fecha de emisión: 2007-05-24
Duración: 70 min
Sinopsis: The arrival of María, the new cleaner, at La Laguna Negra boarding school, after escaping from a psychiatric hospital, will disrupt the peaceful life of Héctor, the charismatic headmaster, who has a seemingly perfect relationship with Elsa, the strict head of studies. A closeness will develop between them that Elsa will try to prevent. María is not the only one fleeing a painful past. Marcos and Paula, after the disappearance of their parents, are taken in by the school under the tutelage of Héctor, who is now their only family.

Everyone has a secret. (Episodio 2) 4.0
Guionista: Laura Belloso
Fecha de emisión: 2007-05-31
Duración: 70 min
Sinopsis: María finds help after being fired. The girls recognize Alfonso's ring on Marcos' finger.

Out of sight, out of mind (Episodio 3)
Guionista: Laura Belloso
Fecha de emisión: 2007-06-07
Duración: 69 min
Sinopsis: Marcos discovers a secret entrance in Alfonso's closet, which opens up a whole new world of questions.

A Message in a Bottle (Episodio 4)
Guionista: Nacho Pérez de la Paz
Fecha de emisión: 2007-06-17
Duración: 70 min
Sinopsis: Carolina pretends to be Alfonso and sends an email to Ricardo Montoya, with whom she arranges to meet at the cemetery. The journalist explains to the kids the disappearance of the five young orphans in the 1970s and warns them of the enormous danger they face if they continue with their investigation. He insists that they should not trust anyone, either inside or outside the boarding school, but the kids are already too involved in the mystery to give up now. Marcos is worried about his sister, who is too caught up in her fantasy world.

A Corpse in the Lagoon (Episodio 5)
Guionista: Ruth García
Fecha de emisión: 2007-06-21
Duración: 77 min
Sinopsis: Héctor discovers the mangled corpse of journalist Ricardo Montoya in the lagoon. After recovering from the initial shock, the boys realize that they have lost the only evidence they had of the death of the five orphans. When they return to the well to try to find more evidence, they see that workers are permanently sealing the entrance. They are told that these are orders from the school administration. From that moment on, accidents begin to occur in La Laguna Negra, and the boys realize that the danger they have been warned about is real. Jacinta is depressed. As always, the postman brings back the letters she sends to her daughter Verónica.

The Night of Saint Elizabeth (Episodio 6)
Guionista: Ruth García
Fecha de emisión: 2007-06-28
Duración: 69 min
Sinopsis: The school mystery culminates with the announcement that a student has been found dead in the woods.

Temporadas

Episodios 6

Episodios 8

Episodios 9

Episodios 11

Episodios 9

Episodios 13

Episodios 15
Episodios 18