The book in question is a speculative fiction novel set in a dystopian future where a sudden and severe ice age has gripped the Earth, leading to the collapse of civilization and the emergence of a new society. The story follows the protagonist, a historian, who discovers the truth about the ice age's origins and the existence of an advanced prehistoric civilization. As the protagonist delves deeper into the past, he uncovers startling revelations about humanity's history and the cyclical nature of human progress and decline, all while navigating the challenges of life in a frozen world.

This gripping novel unfolds in the misty and myth-shrouded Baztan Valley of Navarre, Spain, where a detective returns to her hometown to investigate a series of eerie murders. The victims, teenage girls, are found in a state that suggests ritualistic killings, drawing the detective into a complex web that ties the present crimes to her own troubled past. As she delves deeper, local superstitions and family secrets emerge, challenging her rational beliefs and forcing her to confront the possibility that the answers she seeks might be as intangible as the mythical Basajaun, the invisible guardian of the forest. The story masterfully blends elements of crime, folklore, and psychological thriller, creating a suspenseful narrative that keeps the reader guessing until the very end.