Monday, November 3. Police detective Sarah Lund is about to leave her job in Copenhagen to move to Sweden. Troels Hartmann is gaining ground in his efforts to lead his party to power at city hall. Theis and Pernille Birk Larsen are the happy parents of three children. The discovery of the blood-stained belongings of a young girl prompts a police investigation that will change the lives of all involved.

Friday, November 7-Saturday, November 8: Lund and Meyer investigate teacher Raman al Kemal's actions on the night of the murder. Hartmann learns of foul play at city hall, and his campaign is put under pressure when his opponent reveals Hartmann's ties with the suspect in a TV debate. On the day of Nanna's funeral, Lund is finally on her way to Sweden, and the appearance of one particular guest makes Nanna's father offer him a ride home.

Saturday, November 8-Sunday, November 9. Lund decides to stay in town to continue the investigation even though it puts her relationship with Bengt under strain. Rama is questioned as the main suspect. When Hartmann chooses not to suspend him, it puts his political position under threat.

Sarah has walked into a life-threatening situation.

Lund and Meyer become convinced there is a link between Nanna's murder and a case that has remained unsolved for 15 years, and frantically try to find evidence. Meanwhile, Pernille and Theis are confused by the fact the case is far from closed, and Hartmann puts everything on the line in a bid to win the election.

Lund is determined to catch Nanna's killer despite being taken off the case, and Hartmann is on a downward spiral - until he receives crucial information. Meanwhile, Pernille and Theis invite friends and family to Anton's birthday party - but there is a sinister twist to the evening in store.