Bernard Samson (Ian Holm) has returned to Berlin with a mission to sniff out a suspected traitor who threatens the security of his Brahms network.

Bernard Samson (Ian Holm) is a marked man following the exposure of his wife, Fiona, as a traitor. Meanwhile, a KGB agent in Mexico wants to defect to the west.

Bernard Samson (Ian Holm) attends a lavish Christmas party in Berlin, in the hunt for a traitor. Stinnes offers information about a KGB spy cell operating in Oxford.

Bernard Samson (Ian Holm) has to oversee one last operation to trap the KGB, and to test the sincerity of Stinnes's defection.

Bernard Samson (Ian Holm) finds double-dealing on both sides of the Berlin Wall, but uncovers the identity of the suspected mole in the Foreign Office.

Bernard Samson (Ian Holm) confronts the suspected mole in the Foreign Office. Meanwhile, in Berlin, Volkmann and his wife are playing a curious game of intrigue and deception.

Bernard Samson (Ian Holm) is caught in a deadly spiral of distrust and violence, and his actions lead to a death in custody.

Bernard Samson (Ian Holm) goes to Mexico to try to turn Stinnes.

Bernard Samson (Ian Holm) and Gloria are babysitting Soviet defector Stinnes in London, but developments at London Central lead to a deadly turn of events.

Bernard Samson has spent most of his life in Berlin. Following in his late father's footsteps, he worked for British Intelligence during the Cold War period. After losing a member of his East German spy group while trying to cross back into West Berlin, he loses his nerve and has spent the last few years behind a desk in London. The other members of his Intelligence group are Oxford- and Cambridge-bred bureaucrats with no field experience. Bernard is an anachronism, a dinosaur -but they need him. There is a mole working in London Central leaking secrets to the Russians. Bernard is called out of semi-retirement to go back to Berlin and make contact with his old spy group and try to find out who the mole is. But who can be trusted? He calls upon his oldest friend Werner Volkmann for help.

The suspected mole has been killed, and a traitor in London Central itself is implicated. Samson goes to East Berlin to investigate, but the KGB are prepared for his arrival.

Bernard Samson (Ian Holm) tries to prove his own loyalty by master-minding an operation to secure the defection of a KGB officer from Mexico.

Samson's father-in-law threatens legal action to secure custody of the children. Bernard Samson (Ian Holm) receives a surprise visitor. Mackenzie is found dead in an MI6 safe house.