An Oslo detective with a painful past returns to his native Iceland to help a dedicated cop hunt a serial killer with a link to a mysterious photo.
Following a brutal murder at Reykjavik's harbor, an ambitious but frustrated police detective is tasked with tracking down the killer.
With a new detective on the team, police turn their attention to the wayward son of one victim and search for a connection to the other.
A witness offers a much-needed — but distressingly vague — lead. Arnar scours a new video for clues. Kata grows more concerned about her son.
Arnar suffers a loss and Kata crosses a line. Meanwhile, public pressure to solve the murders grows stronger following a televised interview.
As Kata and Arnar make headway in their search for a suspect, a leak to the press puts the investigation — and lives — in jeopardy.
After the Valhalla case is seemingly wrapped up, Arnar learns of several odd inconsistencies regarding one of the murders.
As new evidence points them down a dark path, Kata and Hakon make a bold request of their higher-ups. Meanwhile, Arnar rethinks his family.