It's October 1981, the height of the Cold War, where political tensions are high and the threat of nuclear war is never far. It's a cold night on Soviet submarine U-137, but the crew are keeping warm with a raucous party to celebrate a new father in their midst. One drink leads to another, and the submarine ends up running aground in neutral Sweden on the Karlskrona archipelago, only a stone's throw from the nations top-secret naval base." Whiskey on the Rocks" is a playful retelling of this unbelievable true story that explores the catastrophic fallout of this boozy mistake. Never before has the world been closer to a nuclear conflict, and all responsibility now rests on the shoulders of one man to de-escalate various warmongers ambitions, Sweden's Prime Minister Thorbjörn Fälldin.

Prime Minister Thorbjörn Fälldin hastens to Stockholm where he gathers representatives of the government and military. The Bolshevik-hating Commander-in-Chief, Börje Lagercrantz, argues that Sweden is under attack and that the only reasonable course of action is to counter-attack, but the Secretary of State, Ola Ullsten, advises caution, prompting Börje to leave the meeting in a fury. On the submarine, the situation for Captain Peskov and his crew becomes increasingly desperate. The submarine is firmly stuck and they are fearful of the punishment they will receive when (or if) they do get home. New orders come from the Kremlin that Captain Peskov must blow up the submarine if the Swedes try to board the vessel, an action that is a tempting solve to most of his problems.

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.