Ten days after lawyer Anne Dragsholm was found dead at a WWII memorial, the police have her husband in custody for her murder. But the chief of investigation calls on Sarah Lund, who has transferred away from the crime squad, to return to Copenhagen to look over the case. Meanwhile, a young politician is made minister of justice after his predecessor is incapacitated, and a convict seeks parole from a detention facility to be with his wife and child

Sarah Lund officially joins the investigation into the murders of Anne Dragsholm and soldier Allan Myg Poulsen, who was found butchered in a warehouse. A published video of the captive Dragsholm suggests the assassinations are acts of terrorism, and the police look into links with Islamic extremists. At Parliament the case puts new minister Buch's terrorism legislation in jeopardy when the government's right-wing partners demand a tighter grip on extremism. Prisoner Jens Peter Raben takes matters into his own hands after being denied parole.

While intelligence services insist that the investigation should focus on possible terrorism links, Raben's escape strengthens Lund's interest in his links with the victims. Raben himself seeks information from other old army buddies. Buch is hit by the revelation of a secret memo about the Dragsholm murder, and the actions of the former minister come into question.

The murder of another former soldier, David Grüner, prompts inquiries into his and Raben's army squad and a particular event during the group's Afghanistan mission a few years before. Lund and Strange track down one of the remaining members in a remote Swedish island. Buch is under pressure from above to cave to the right wing's demands about banning Islamic organisations, but new information about former minister Monberg's relationship with one of the victims makes him weary of acting too hastily.

The police investigation comes under fire after soldier Lisbeth Thomsen was killed by a bomb planted in her boat, but Brix keeps Lund and Strange on the case. They try to learn the truth about the Afghanistan mission and pay a visit to the mother of a fallen soldier who may be connected to the case. Buch causes scandal when he interrupts his own press conference, and the prime minister wants him to come up with answers. Raben remains on the run, but seeks help from his former comrade the chaplain.

Lund demands that the grave of the dead soldier Per K. Møller be dug up, but her theory that the coffin is empty is proven wrong. She is suspended from the investigation and takes time to attend her mother's wedding until developments bring her back into action. Buch brings his assistant Karina Munk back after she resigned, despite permanent secretary Plough's objections. They pay a visit to former minister Monberg, who has gained consciousness at the hospital, to find out what he knows about the ongoing case.

After finding the chaplain assaulted in his church Sarah Lund chases the offender, but ends up battered in an alley. She is brought back in charge of the investigation. Monberg has taken his own life shortly after his confrontation with Buch. Buch comes about a previously unknown medical report and decides to challenge his colleague the minister of defense over his secrecy. Raben continues his rogue investigation and tracks down a former soldier who he believes to be responsible for the Afghanistan incident.

Jens Peter Raben has been shot by Strange during an escalated situation where Raben seemed to recognize Strange. Raben survives, and Lund finally has the chance to interrogate him. She finds herself investigating her partner's past in the military, but also uncovers a soldier's video diary that leads to a new suspect. At the barracks Colonel Jarnvig begins to consider the possibility that Raben's version of events in Afghanistan might be true. And after a week in the job Buch faces forced resignation, but finds help from an unexpected source.

Thomas Buch has refused to resign and calls a party meeting to challenge the authority of the prime minister. He finds an unexpected ally in the minister of defense. Lund and Strange head to Afghanistan to seek out Frederik Holst, a doctor with a grudge against Raben and his squad. They also decide to visit the house where a family was allegedly killed while the Danish soldiers were there. Back in Copenhagen, Brix organizes a search of the army barracks and finds a locker full of incriminating objects.

Lund and Strange return from Afghanistan with their findings, though Brix has become convinced of the guilt of officer Bilal, who has run away with Louise Raben as his hostage. Buch has been held overnight by the police, but returns determined to bring down the government he is part of. Secrets are uncovered at the ministry and in the military, revealing a conspiracy to conceal vital information. Lund puts together some pieces of her own, and it comes to a lethal confrontation with the killer.

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.

Monday, November 3-Tuesday, November 4. Nanna's parents identify her body, and details of her sufferings are uncovered. Lund keeps postponing her departure, and tension arises between her and her new partner as they investigate the connection to city hall and a known criminal identified as the driver of the car Nanna was found in. Hartmann is faced with the choice of cooperating with the police or protecting his political future.

Tuesday, November 4-Wednesday, November 5: Lund and Meyer track down the driver, who ends up injured in the hospital, but also supplies an alibi. They refocus their investigation on Nanna's school. When the story of the connection to his campaign breaks, Hartmann finds himself in media turmoil. The Birk Larsens try to cope with their loss as they arrange the funeral.

Wednesday, November 5-Thursday, November 6: The police investigate the crime scene they have found at Nanna's school and suspect her classmates Oliver and Jeppe of wrongdoing. Sarah Lund's fiancé shows up in Copenhagen, and she promises to leave for Sweden without delay. Meanwhile, Hartmann learns that a trusted employee has sent a suspicious email.

Thursday, November 6-Friday, November 7. Hartmann has won a new political ally, but is drawn into the murder case again when the police uncover new information which turns their suspicions towards teachers at Nanna's school. Theis Birk Larsen is troubled by the financial strain of the house he bought before Nanna's death. He begins to grow weary over the lack of progress in the case and seeks his own sources of information.

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.

Sunday, November 9-Monday, November 10. The police locate the place where Nanna was killed, and Rama is charged with the crime. Hartmann is fighting for his political life, but ends up making a tough choice. Meanwhile, Bengt is in a car accident on his way to Sweden, but tries to help Lund from his hospital bed. When the evidence is cast into doubt, Rama is released, but someone has other ideas.

Monday, November 10-Tuesday, November 11. Theis Birk Larsen's brutal punishment of Rama is interrupted by the police, and Theis is arrested. Lund and Meyer refocus their investigation on the car used by the murderer, knowing that if they do not make progress they might be taken off the case. As it becomes known that Rama is no longer a suspect, Hartmann shakes things up at city hall and relaunches his campaign.

Tuesday, November 11-Wednesday, November 12. Bengt leaves for Stockholm. Lund and Meyer are hindered in their investigation by a secretive boss, but Lund continues inquiries and is dismissed for her sins. Hartmann strikes a deal with higher powers in order to secure his bid for mayor, and a public debate is the scene of a change in political fortunes. Theis is released from prison, new secrets are uncovered about Nanna's last months, and in a last bid to forward the investigation, Lund unlocks the door to a new piece in the puzzle.

Sarah and Jan know who they are looking for but are puzzled by their superiors' reactions.

Sarah and Jan interrogate Troels, whose private information opens a new can of worms.

The spotlight of the police and media is now trained on Troels Hartmann, and he feels his political career is crumbling. Meanwhile strange things are going on at the town hall with fatal consequences.

Troels's political opponent Bremer wastes no time in taking advantage of his discomfort.

Sarah has walked into a life-threatening situation.

Sarah won't get on board when her superiors insist that Nanna's murder has been solved.

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 and Meyer get more than they bargained for when they visit an abandoned warehouse in their search for evidence. Meanwhile, a prime suspect disappears, and Hartmann struggles to get back into the political arena - but is contacted by a journalist whose efforts to dig up dirt have had some success. Theis and Pernille try to move on from the past 18 days' events and take their sons to see the new house.

Lund finds the odds stacked against her as the search for a missing suspect takes an unexpected turn, and Hartmann and Bremer take part in a dramatic, live TV debate amid a stream of revelations. Meanwhile, it seems something is amiss as Theis and Pernille prepare to move into their new house.

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.