A little girl playing in Djupelv finds the remains of a body. The family don't want to get involved so tip off the police anonymously. However, later that day the girl runs off from home and mysteriously disappears.
In spite of warnings, Thomas begins investigating Silja's death, and discovers a seemingly abandoned sawmill that holds macabre secrets.
During an arrest, a suspect is shot and killed by a recruit before the police get to question him. A newspaper puts the story on its front page, but Mia finds completely new information that turns the case on its head.
Several clues point to Thomas' own family, but there are some who are determined to prevent him from revealing the truth and derail the investigation.
Thomas and Mia discover that the police and the armed forces are concealing a great scandal from the Cold War. They escape the village with special forces at their heels, so decide to head to Russia to uncover the whole truth.
Mia and Thomas are on their way to Russia to find the infamous double agent. But they are being chased and their predicament becomes rather fraught.
Thomas and Mia cross the border to Russia, and speak to a retired agent who sheds new light on Thomas's family.
The mystery surrounding Silja's death is explained. High on the mountain lies the solution – a horrible secret that the armed forces have tried to cover up for all these years.
