Following an earthquake, the water level of an Icelandic lake suddenly falls to reveal a skeleton half-buried in its sandy bed. It has clearly been there many years. There is a large hole in the skull. Yet more mysteriously, it is weighted down by a heavy radio transmitter bearing inscriptions in Russian. The police are called in and Detective Erlendur and his colleagues begin their investigation. It takes them back to the Cold War era, when bright, left-wing students in Iceland would be sent to study in the 'heavenly state' of Communist East Germany. A trail begins to emerge, from the hopes of youth to international espionage and murder. It will take some time, however, before this episode gives up its secrets, or its various betrayals are avenged.