The entire plot of "Dr. Strangelove" is a slow, inevitable march towards a foregone conclusion: the end of the world. The central twist is not a single event, but the gradual realization by the characters and the audience that there is no way to stop the catastrophe. The critical turning point comes with the revelation of the Soviet's secret "Doomsday Machine," a device that will automatically trigger a worldwide nuclear holocaust if the USSR is attacked. This nullifies all of the frantic efforts in the War Room to recall the bombers or mitigate the damage. The point of no return is sealed when General Ripper commits suicide, taking the only recall code for the bombers with him.
The film's climax is twofold. First, Major T. J. "King" Kong's B-52 bomber, its communication systems damaged, successfully reaches its target. When the bomb bay doors malfunction, Kong manually releases the bomb, riding it down to its destination in a now-iconic, rodeo-like display of phallic triumphalism. This act triggers the Doomsday Machine. The second part of the climax occurs in the War Room. As the reality of their doom sinks in, Dr. Strangelove enthusiastically outlines a plan for humanity's survival, which involves a select group of elites living underground in mineshafts with a high female-to-male ratio for repopulation. His cold, eugenicist excitement culminates in him miraculously rising from his wheelchair and shouting "Mein Führer, I can walk!" This final line reveals the ultimate hidden meaning: the apocalypse is not just a failure of systems, but a horrifying rebirth of humanity's most monstrous, fascistic ideologies. The film then cuts to a montage of real nuclear explosions set to the ironically optimistic Vera Lynn song "We'll Meet Again," confirming that the Doomsday Machine has been activated and all life on Earth is being extinguished.