Two years after losing her badge, Sarah Lund is now a border guard. But when the body of a woman is found battered and killed, her former boss Brix calls on her to do what she does best: solve what's shaping to be a highly complicated case.

The police now have two murder cases. When Sarah finds a connection between them, she and new partner Ulrik Strange must investigate several secretive circles. In Parliament, Secretary of Justice Thomas Buch deals with a publicized terror threat.

Ex-soldier Jens Peter Raben makes a bold move that puts the police spotlight on him. When resident Islamists are arrested, Sarah and Ulrik disagree on which leads to follow. Buch is plagued with problems in Parliament.

The police discover yet another murder victim, and everything indicates that it's the same perpetrator from the previous crimes. Under pressure from the Opposition and the Prime Minister, Buch learns something surprising about his predecessor.

Sarah and Ulrik are in Sweden to question and protect an important lead, but Raben is on the same mission. Meanwhile, Buch makes trouble in Parliament and resorts to unconventional measures. Sarah sees the case from a new angle.

Sarah is convinced that there's something off about one of the murder victims. Buch's fellow ministers have run out of patience but he wants to know more about what his predecessor was up to. Things come to a head at the police headquarters.

When Sarah pursues the killer, she finds herself in serious danger. Buch's predecessor makes an escape after Buch pressures him to reveal information about an old case. Raben is still on the run, but Special Branch is keeping a watch on him.

After his encounter with Ulrik, Raben's situation does not look good. Sarah and Brix dig into Ulrik's past, and Brix makes a drastic decision. Buch's criticisms of the Minister of Defense over Afghanistan are decisively refuted.

Sarah and Ulrik have gone to Afghanistan to track down the killer, with shocking results. Back home, Brix decides to conduct a search at the army barracks. Buch is convinced of a cover-up and continues to generate turmoil within the cabinet.

The trip to Afghanistan has produced conclusive evidence on the identity of the killer, while Brix discovers important findings in the investigation. While there is talk of the prime minister reshuffling his cabinet, Buch develops a new suspicion.