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.

Hamilton and Kristin arrive in Hamburg to help BND in the hunt for the terrorists. Astrid investigates Elena's death. DG finds out that Hamilton is a double agent working for the CIA. American security-specialist Pence convinces Swedish State Secretary Gripenberg to pay off the cyber-terrorists responsible for the hospital outage, preventing them from carrying out further attacks. Unfortunately, they are unable to prevent Norling's death. Hamilton tracks the terrorists to a warehouse in central Hamburg.