Thomas and Mia try to track down all of the marine commandos who have come up in the investigation. Meanwhile, they find out that Officer Cronwall is missing. His wife is deeply remorseful. It turns out that Cronwall lied, he had met Marcus. But where is Cronwall now? Did he disappear intentionally, or was he kidnapped? And who murdered the former marine commandos? Old diaries from this period in the Marine Commandos turn up and provide some answers. The investigation leads back to Korsö, where the ultimate revenge has been planned. Both Nora and Thomas are there in the final thrilling pursuit of the killer. But will they make it in time to save the final victim...?