The postcard killers

New York police detective Jacob Kanon searches for the killer of his daughter and her boyfriend, who were murdered while on vacation in Rome. Since then, young couples in other European cities have been found dead with little to connect the murders except a postcard to the local newspaper. Kanon teams up with the Swedish reporter Dessie Larsson, who has just received a postcard in Stockholm, and they think they know where to find the next victims.