After fighting the communists in Finland, Max Manus returns to Norway, currently occupied by the Nazis. He joins with the Norwegian resistance movement in their fight against the Germans but is arrested. He manages to escape to Scotland where he receives training before being sent back to Norway to carry out various sabotage missions against the occupational force.
Returning to Norway with his friend Gregers Gram, his first mission is an attack on German supply ships. He is spectacularly successful, and soon he becomes a special target for the Gestapo commander Siegfried Wolfgang Fehmer. Manus, however, avoids capture, and with Gram and Gunnar Sønsteby he forms the so-called "Oslo-group".
Stockholm becomes a meeting point for Norwegians in allied military service. Here Gram introduces Manus to Tikken, who works as a Norwegian contact for the British consulate. The two soon develop a special relationship.
As the war becomes more and more brutal, many of Manus' friends lose their lives in the struggle against the Germans, and he starts to blame himself for being the one who survives. In a meeting with Fehmer he realises that everybody is a victim of the meaninglessness of war.