Amaia Salazar, a police inspector in Pamplona (capital city of Navarra; north to Spain), is sent by her superior to investigate a murder due to her personal relation with the place of the corpse. The case concerns a teenage girl whose naked body is found at the side of the Baztán river close to little town of Elizondo, Amaia's birthplace, a rainy village surrounded by forests and mounts located in the middle of Baztán's valley, full of local myths and ancient superstitions. Her marriage to James Westford, an American sculptor and artist gallery, is falling apart due to her desire for a child, and despite she never wanted back to her family home, Amaia Salazar is forced to face the past and reconnect with her lovely and tarot's card caster Aunt Engrasi, and too with her older sisters Flora and Rosaura. Helped by Engrasi and her tarot's readings as well as Amaia's former mentor and FBI's agent Aloisius Dupree by video-conference looking for new clues and other point of view to find the killer, Amaia's instinct for criminal cases will be challenged according to more naked bodies of teenage girls are found in the forest, where an ancient myth says that it's protected by a giant supernatural creature named Basajaun, at the same time that she's stalked by her child memories. Trying to solve the case and discover the identity of the killer, Amaia must not only confront her distant and troubled relation with her sisters and her own childhood trauma from the several abuses of her demented mother, who tried to kill her at child, but also the each time bigger suspicion that perhaps the serial killer is someone who is too much close to her and her family, putting all of them in serious danger.