In Kaliningrad, Polish spy Ewa goes undercover to gather critical information on a prominent Russian nuclear engineer.

Ewa helps a key target escape, while Lange works to keep his agents safe. In Riga, Tamara searches for answers.

Amid threats of a dirty bomb attack, Tamara closes in on Ewa’s family, Skiner vows to protect Kaj in Krynki, and Ewa uncovers intel about Skopincev.