Martin is supposed to prevent further liberal reforms from being passed by the GDR government. Following his own plan, he gets caught up in a chain of events that bring the Berlin Wall down. In a fateful encounter he meets Nicole, Max's teacher. Lenora has become radicalized in prison. The HVA must act now.
International secret services interested in Martin offer him the same options: either to be locked up, hired or killed. Eventually, he receives the order to infiltrate a West German terror cell. Rose visits Lenora in prison. Schweppenstette reluctantly accepts a mission in Frankfurt.
When terrorists put Martin to a radical test, he has to face his past. Lenora confronts Fuchs and sets off for Frankfurt with the Romanian agent Grigore. Schweppenstette comes to terms with Beate and his new married life in Frankfurt, and impresses his new managers with his knowledge of the GDR.
Martin arrives in Frankfurt, in the midst of preparations for a major terrorist attack. Desperately, he tries to prevent the ignition of a bomb, and in the process encounters his aunt Lenora. Fuchs and Dietrich are preparing to turn their backs on the GDR forever.
Martin and Nicole follow Lenora, who is seeking shelter with Grigore in Romania. Schweppenstette uses HVA methods to draw a dogmatic state banker to his side. Fritz's company is taking a surprising turn.
Lenora asks Fuchs in Italy, the HVA's new home in exile, for help. Fuchs tries to find a peaceful solution between his former agents, but Martin and Lenora have other plans. Tina receives a mysterious visitor. Martin becomes suspicious of Nicole and her true intentions.
Everyone comes together in Leipzig. Martin tries to prevent Lenora's attempted assassination. Valdez and Brigitte try to stop Lenora with Rose's help. Schweppenstette closes a deal at the Leipziger trade fair. Fritz wins investors. Tina discovers the terrible truth about her visitor.
Martin is kidnapped and has to fight for his life. Schweppenstette tries to save his son while his "wife", Nicole, and Max face an imminent threat in Frankfurt. Tina and Ingrid reveal Tischbier's biggest secret.