The second season aired in Sweden, Denmark, Norway, Finland and Iceland over ten weeks from 22 September to 24 November 2013, and began airing in the United Kingdom on BBC Four from 4 January 2014.
When the coastguard board a ship headed for the Oresund Bridge, they discover three Swedish and two Danish youths chained below deck.
While Saga and Martin are quarantined, someone posts a video online where four individuals in masks use signs to claim responsibility for the plague.
Saga and Martin continue hunting down the eco-terrorists and start profiling them. Martin makes some progress in his meeting with Jens.
Saga and Martin investigate the killing of the eco-terrorists. Saga rules out suicide. Martin hits it off with his Danish colleague Pernille.
An important witness has memory loss. The investigation grows and new clues are received. A new attack is carried out.
A new case of poisoning is linked to Saga and Martin's case. A motor boat is salvaged from the ocean floor.
Saga and Martin have a complicated puzzle to solve when a chemical plant is threatened.
Saga and Martin requestion witnesses and suspect that someone in the group changed the data in the report. Witness Laura wakes up and Martin makes another visit to Jens in prison. Saga tries to find a solution to the problem of cohabitation.
Police now have a phantom image of the offender. Just as Saga and Martin think that the matter is cleared up, it turns out that the great 'end' points towards Heathrow airport. Martin moved back to Mette and Saga and Martin's friendship put to a severe test.