The story begins when a serial killer known as starts leaving a trail of macabre bodies across Bilbao. As Chief Inspector Ander Crespo and his "Group 4" homicide team investigate, they realize these current murders are deeply connected to the cold cases of missing girls from the late 1990s. The investigation eventually forces Ander to confront his own painful past, specifically the disappearance of his sister and the abandonment by his mother. Key Themes & Style

: The book is noted for an agile, addictive rhythm that intensifies toward a surprising conclusion where history and esotericism converge.

: Reviewers on Babelio praise Goikoetxea for treating the winter-chilled city of Bilbao as a character itself, capturing its historical essence and industrial vestige.

: Ander Crespo is portrayed as a "flesh and blood" character, struggling to balance professional duty with a personal drive for justice.