In Karlskrona, Commander-in-Chief, Börje Lagercrantz, is planning his own initiative to approach the submarine in order to measure for the presence of nuclear weapons. Börje has put his best man, Captain Hammarberg, in charge of the unsanctioned operation and, under the cover of darkness, they approach the submarine. Things don't go according to plan when they are detected and the troika barely escape with their lives. In Moscow, Brezhnev finds out about the incident and flies into a rage, contacting the Russian ambassador in Stockholm, Aleksandra Kosygina, demanding she fixes the situation fast. On the submarine, Captain Peskov's psychological condition drastically worsens, and he starts to see no other way out than to blow the submarine to kingdom come.

In his government office, Prime Minister Thorbjörn is visited by the Soviet Ambassador Aleksandra Kosygina. It turns out that their plan to install a radio mast on the submarine has been dashed by the Commander-in-Chief, who happens to have come up with the same plan. In the Kremlin, an increasingly decrepit Leonid Brezhnev is having a hard time dealing with the crisis and gets an unexpected helping hand from the Fourth Chairman of the KGB, Yuri Andropov. However, it quickly becomes apparent that Andropov has ulterior motives in aiding Brezhnev. Meanwhile, Ambassador Kosygina makes a trip out to the submarine accompanied by one of the crew, Commander Anders Karlsson, where she realises she is confronted with the mad Captain. She soon discovers that there is another way to solve the problem.

Prime Minister Thorbjörn visits the naval base in Karlskrona where he comes face-to-face with an unexpected gathering of the international press and media. In the meantime, Commander-in-Chief Börje is preparing an unsanctioned attack against the submarine using his own elite forces. When news about Börje's plans to attack the submarine reaches Thorbjörn, his patience is tested and he decides to use unorthodox methods to put a stop to Börje's rebellious attitude. Unfortunately, both the KGB and CIA have intercepted this plan, escalating tensions further. Back in Stockholm, Secretary of State Ola Ullsten is struggling on several fronts. When he is confronted by both the KGB and CIA, it all comes to a head and it seems that everyone knows more than him.

Prime Minister Thorbjörn holds a press conference in Government Offices in Stockholm. When he reveals that the submarine is equipped with nuclear warheads, a chill passes through the room. Thorbjörn and Soviet Ambassador, Aleksandra Kosygina, finally manage to solve the Gordian knot, but is there enough time to free the submarine from the reef before a conflict ensues? NATO forces have arrived in the area, and the Russian fleet looms nearby, readying themselves to attack, urged on by a drunken Brezhnev. On board the submarine, it turns out that there has been a mutiny. As tensions rise, the world holds its breath.