Danish drama set in Copenhagen during World War 2, based on real events and eyewitness acounts. Flame (Thure Lindhardt) and Citron (Mads Mikkelsen) are the code names for two undercover resistance fighters working for the Holger Danske group, which works to undermine the Nazi occupation. The younger and more idealistic Flame fantasises about launching an open attack on the Nazis, while sensitive family man Citron is more concerned with the politics of resistance. But when their boss Aksel Winther (Peter Mygind) orders Flame to execute his girlfriend, beautiful and enigmatic courier Ketty (Stine Stengade), he finds himself questioning the morality of the order. Finding themselves in an increasingly claustrophobic situation, the two men realise they have only each other to rely on, and work together to track down Gestapo chief Hoffmann (Christian Berkel).