As a gruesome and perplexing murder strikes Oslo, a personal tragedy drags Harry back into bad habits and an obsessive search for answers.

After crossing one line too many, Harry is reassigned to a missing persons case that raises his suspicions. Waaler sets a trap with lethal consequences.

The police must call on Harry’s expertise after a chilling package arrives by post. But with Waaler leading the case, his return comes at a price.

With evidence suggesting they're dealing with a serial killer, the police shift tactics and chase a promising lead as gang violence escalates across Oslo.

Unable to find a logical connection between the symbolism, locations and victims, Harry attempts a mind-bending method to crack the serial killer’s code.

Patterns and riddles point Harry in the direction of the next possible murder. But is he finally one step ahead, or still chasing the killer’s tail?

Hunted by his own, Harry goes underground with his captive to prove a theory — only to uncover another deceptive layer separating him from the truth.

Harry closes in on the secret behind the murders, but as his worst fears surface, the cost of his relentless pursuit of justice becomes alarmingly clear.