Denmark is the midst of a fiercely contested election race, set against the backdrop of the financial crisis. With ten days to go to the election, Detective Chief Inspector Sarah Lund prepares to celebrate her 25th year in the police force and looks forward to the prospect of a new job in the force. But her relative peace is shattered when body parts are found at Copenhagen dock only hours before a scheduled visit by the prime minister.
Another failed exchange attempt puts Borch and Lund in a dilemma: should they obey the perpetrator, or act despite his directives - and thereby risk putting Emilie Zeuthen life further at risk? The coroner's death suggests several things now that there is a relationship between an old murder and Emilie Zeuthen's fate. Robert Zeuthen is ready to pay the ultimate price to get his daughter back alive, and despite police warnings, forces through his will. The Prime Minister's political life is linked more and more with an unsolved police matter, and Minister of Justice and PET cannot provide clarity. Opposition leader Ussing takes every opportunity to accuse Kamper of responsibility for Emilie Zeuthen's disappearance.
Sarah Lund is held back in her attempts to make headway with the investigation, but at least the perpetrator finally has a face. Will he lead police and the Zeuthens to Emilie? Prime Minister Kamper is trying to clean up his circle as he attempts to find out what happened to his son. Suspicions arise about a trusted Zeeland figure as Robert Zeuthen considers drastic action.
Borch has got Lund back on track in the case of Emilie, and they're now working with Asbjørn looking for signs of life. They follow in the perpetrator's tracks, who obviously has gone to Jutland looking for something, but what? They make an eerie discovery, and expose themselves to danger. At the same time Lund and Borch are faced with a dilemma. The pressure on Brix grows at police headquarters, as management ask questions about his judgment. Robert and Maja find it hard to believe that their daughter is dead, but they try both to deal with the debilitating grief that has befallen them. Preparations for the funeral begin. Prime Minister Kamper struggles with his decision, because he understands that doubts have arisen about Emilie's fate, but the Minister of Finance is not easy to convince. Ussing turns out to have a secret that gives Kamper new faith that he can regain the party's trust.
A new element turns out to play a role of great significance in the investigation. Borch and Lund have a hard time shaking off their Jutland experience, and their working relationship suffers as a result. Robert and Maja harbour hopes that Emilie may still be alive and Zeeland throw all their resources into tracking her down, as a secret is revealed from an unlikely source within the family. Police run checks on Ussing's movements over the last couple of years.
After the dramatic death of the deputy public prosecutor, it is clear that Emilie Zeuthen's kidnapper is a man who will stop at nothing to recover a debt. But what is this debt? Lund and Borch are trying to get cooperation, and Lund tries to get Mark to reconcile with her. The family Zeuthen find it hard to accept that Emilie is gone, and press the police to act by making all resources available. Prime Minister Kampers staff are trying to keep him free of the kidnapping affair, but they have some unpleasant information, which makes it difficult to focus on the election campaign.
The perpetrator continues to talk about a debt that he will have met and if Sarah Lund is to save Emilie's life, she must find out which debt he's talking about, and how it should be paid. The perpetrator has this time asked for Robert Zeuthen in exchange for Emilie - the exchange is in progress. Robert Zeuthen is now on the way, along with Lund, to sacrifice his life for his daughter, while Maja follows the drama from Police Headquarters, where Brix tries to get a handle on the situation. The Minister of Justice proves to be crooked, and the same applies to Anders Ussing. Their possible connection to the old murder gives Kamper reason for serious considerations, and he makes a dramatic decision, much to the frustration of both 'stoffer and Karen.
A suspect is taken in for examination as the police try to find out more about the notebook they discovered, but things go less than smoothly. The prime minister and his close aids become the focus of police attention, as Karen is also found to be hiding a dangerous secret which could prove fatal for the government. Borch and Lund's trip to Jutland begins to have consequences. Robert Zeuthen intensifies the hunt for his daughter, despite coming under heavy pressure from the Zeeland board. Maja takes sides. A witness turns up who may have important information about Emilie.
It's election day and the Prime Minister has everything to gain, as long as Emilie's fate remains uncertain. Kamper is still haunted by personal demons, and issues of loyalty from within his own ranks rear their ugly heads once again. Meanwhile, as Lund and Borch start to look ahead, police are led to an undisclosed location in a last ditch attempt to find Emilie before it's too late. They are followed by a now dangerously tense Robert Zeuthen. Will the operation succeed in bringing the girl to safety?
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
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.
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.
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.
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.