The Invisible Guardian

The most successful Spanish mystery of 2013.
A young woman is found mysteriously murdered on the banks of the Baztán River, one of the most magical places in the Basque Country. Almost twenty-four hours later, a link is made to the month-old murder of another girl.
Amaia Salazar, the homicide inspector assigned to the case, returns to the place where she was born and where she has always wanted to leave. Amaia is fighting on two fronts: on the professional one, investigating a series of murders that is deeply disturbing the local population; and a personal, intricate and emotional one that will be full of twists and turns and surprising moments.
Amaia is chasing a ritual killer, inspired by the strong psychosexual symbolism of traditional Basque mythology, who will continue his rampage, while she battles the professional jealousy of some of her colleagues, against ancient unresolved conflicts with her sisters and a dark secret, that marked their childhood and that is coming back, to continue to torment her.