It is just an ordinary day, but General Jack D. Ripper (below) has plans. In the air over the Pacific, the crew of a B52 on general patrol receive a coded message from base telling them to attack their targets in Russia. The code checks out - and the world suddenly finds itself a couple of hours from all-out nuclear war.
In the Pentagon's War Rooms, the Generals and Chiefs of Staff gather to brief the President, who is naturally aghast that someone other than him could have ordered bombers to attack Russia. It is pointed out to him that this is a sensible security precaution: if Washington were to be hit by a pre-emptive strike, or the President and Vice-President were otherwise both killed, someone else would need to know the code. The President demands that the bombers be recalled but this cannot be done except by General Ripper himself.
Ripper, on the other hand, has closed his air force base and barricaded himself in his office with Captain Mandrake, to whom he explains his theories about Communist infiltration. He knows the recall code but will not release it. He has also ordered the base personnel to fire on anyone approaching the base, knowing that the Pentagon will try and send American troops in to get the code.
Meanwhile, back in Washington, the President has called in the Soviet ambassador and they try to warn the Soviet Premier of the attack by phone: not easy, as the Premier is drunk:
The President tells the Premier that they will have to shoot as many bombers down as they can. Perhaps only one or two will get through. But the Ambassador has more shocking news. The Soviet Union have a "doomsday device", which, if any bomb hits their territory, will explode and scatter enough radiation into the atmosphere to poison the world for a hundred years. They were due to announce its existence in a few weeks' time.
Attacks are launched against the bombers and some are brought down. The B52 we have been following through the film is damaged, but not grounded. Unfortunately its code machine is broken and it is now out of contact with the air force base, where a full-scale battle is going on between American soldiers. Knowing he is beaten, General Ripper shoots himself, but Captain Mandrake, deciphering doodles on his pad, works out the code and the bombers are recalled....
.... all except the one with the damaged code machine. Too late, the celebrating War Room realise one bomber is still going. The bomb is stuck in the cargo doors, but in his final act, Major Kong (the head pilot) knocks it out and rides on it down into oblivion:
The film ends with the sinister Dr. Strangelove explaining to the War Room that they can retreat into mineshafts to ride out the fall out. Meanwhile, outside, mushroom clouds flower to the sound of Vera Lynn's We'll Meet Again.