In Copenhagen an underground train judders to a halt and masked men take 15 passengers hostage. Philip Norgaard of the Counter-Terrorism Task Force heads a hastily convened team to lead the rescue effort. Philip is an ex-serviceman who has had his own experience of hostage taking, but his first challenge is to determine who are these men, and what they want.

Naja Toft is receiving commiseratory social media messages on having been fired, when she gets another call from Alpha asking for another interview - but this time on her blog. The intelligence team work through the mobile phones left on the train to garner as much information as possible about the hostages. Adel is striking up a friendship with co-hostage Denise who attempts to persuade him to curb his hostile acts towards their captors as it is putting everyone's lives in danger.

Philip is planning an armed response to the first hostage execution. As the mission is risky it creates a rift in the negotiating team.

TTF is getting closer to the hostage taker's identity while Naja gets second thoughts with regards to facilitating the fund-raising campaign, but then she meets Jonas, the hostage Leon's son.

In the garage the police find a wall with newspaper clips of Philip's time as a hostage. Naja is asked to do another interview with a hostage, and this time the police want to make Naja an allie. The hostages try to take matters into their own hands by attacking one of the terrorists during the interview.

With the hostage Bodil just killed by the hostage takers, the police's work keeps growing. TTF's investigation leads them to sources in the Danish military and they seem to be close to a breakthrough.

Philip learns the identity of the main hostage taker and is choked about his personal involvement in the case that leaves a role for Naja to play as well.

Philip goes down into the metro himself hoping to free the last three remaining hostages and is confronted by the man he thought was dead.