Anna Fekete, who fled the Yugoslavian wars as a child, has just started working as a criminal investigator in a northern Finnish coastal town, when she is thrust into a rolling murder investigation. It doesn't help that her middle-aged new partner, Esko, doesn't bother hiding his racist prejudices. Anna's work as a criminal investigator barely gets off the ground before she is thrust into a high-profile, seemingly unsolvable case that has riveted the nation. A young woman has been killed on a running trail, and a pendant depicting an Aztec god has been found in her possession. Another murder soon follows. All signs point to a serial killer, but can Anna catch the Hummingbird before he – or she – strikes again?