When Carl Hamilton returns home from a secret CIA-program in the United States, Stockholm is hit by a series of bombings and cyber-attacks. Hamilton kills the suspected terrorist Rashida after a violent encounter but is unable to stop the attacks. Home Secretary Lindgren, whose secretary Norling is injured in the attacks, demands to find those responsible. SÄPO (Swedish Security Service)-agents Kristin and Birger initiate a hunt for the terrorists, which soon forces them to go beyond the confines of their job description.

Hamilton returns to Sweden, starting off his homecoming with meeting Sonja. Kristin and Birger make progress in the hunt for the terrorists and discover that they are hiding on a ship headed for Germany. Hamilton sets up a secret meeting with his CIA-boss, Haig. DG and his colleague Astrid begin to investigate how the murder of Elena's boyfriend Borisov is connected to the terrorist attacks. DG gives Hamilton a mission to infiltrate Borisov's office at the Russian embassy.