Having blamed Red for years for the bombing that eradicated his Russian resistance cell and caused his daughter’s death, Berlin is stunned when he learns his daughter Zoe is still alive. When Berlin expresses his anger at Red for his exile to a gulag and exposing his daughter as a dissident, Zoe reveals that in order to protect herself from her own father, she arranged to go underground with the help of a man called the Decembrist. Meanwhile, even though Liz has kept him imprisoned for months in an old cargo ship, Tom still refuses to reveal Berlin’s true identity. After Liz narrowly avoids having her shipboard jail uncovered by the harbormaster, Red tells her that Aram has identified the Decembrist as Russian Finance Minister Kiryl Morozov.
As Cooper is warned by his boss to steer clear of the Russians, Liz is summoned to the ship where she finds Tom and the Samoan holding the harbormaster hostage. When Liz refuses to kill him to keep them from being exposed, Tom takes matters into his own hands and strangles the harbormaster. Acting on the news about Morozov, Red and Berlin head for Moscow where they lure him into an ambush. After Berlin demands to know the truth about the bombing, Morozov tells them he was acting on behalf of the real Decembrist, whom he identifies as Assistant Director of National Intelligence Alan Fitch. Berlin kills Morozov and says he’s going after Fitch, even after Red tells him he wants Fitch for himself. Back in Washington, Red confronts Fitch about being the Decembrist and warns him about Berlin, but as he’s on his way to a safe house Fitch is kidnapped by Berlin’s men. Now that he knows Tom is alive, Red presses Liz to use him to find Berlin and save Fitch. When Tom insists on his freedom before disclosing the information, Liz reluctantly agrees. When a SWAT team arrives they find Fitch wired with a bomb.
With the bomb squad racing against time to disarm the explosive device, Red arranges for Berlin to see Zoe one last time before giving her a new identity and sending her on her way. After Berlin insists he doesn’t know how to dismantle the bomb, Fitch summons Red to a meeting and gives him the combination to a safe in St. Petersburg containing information about a secret plot just before the bomb explodes. With Fitch dead, Red returns to Berlin and, after reminiscing about their past, kills him. Finally, after Liz admits to lying about Tom’s death, Red gives Tom an envelope filled with cash and insists he never see her again. Before leaving, Tom assures Red that he never told Liz anything about their relationship.