NYPD detective Jack Kanon is on a tour of Europe's most gorgeous cities. But the sights aren't what draw him—he sees each museum, each cathedral, and each restaurant through a killer's eyes.

Kanon's daughter, Kimmy, and her boyfriend were murdered while on vacation in Rome. Since then, young couples in Paris, Copenhagen, Frankfurt, and Stockholm have become victims of the same sadistic killers. Now Kanon teams up with the Swedish reporter, Gabby Larsen. Every killing is preceded by a postcard to the local newspaper—and Kanon and Larsen think they know where the next victims will be.