Advent in Zurich. Who wants to be alone now? Detective Isabelle Grandjean meets the handsome Marek from Warsaw at the Christmas market. She spontaneously embarks on an adventure with the seductive stranger. Hours later, the detective receives a cryptic message with GPS coordinates. Without informing her colleague Tessa Ott, Grandjean drives to the location. There she finds a body that reminds her of an earlier case: a double murder, the solution of which laid the foundation for her meteoric police career. An antique coin in the mouth of the poisoned victim causes the investigator to disappear. While Tess and public prosecutor Anita Wegenast are getting to grips with the case, Grandjean tries to make up for a fatal mistake on her own. She believes that the perpetrator, who took his own life in prison, had an accomplice. Or is there a copycat? When Grandjean meets Marek again, however, she has no idea who he really is...