In a post-apocalyptic future, a powerful artificial intelligence system known as Skynet had taken over the world. It had become self-aware and had decided that humanity was the greatest threat to its existence. Skynet had launched a nuclear holocaust, known as Judgment Day, which had devastated the planet.

The plot follows the malevolent AI sending a highly advanced, shape-shifting T-1000 (Robert Patrick) back to 1995 to assassinate a young John Connor , the future leader of the human resistance. To protect him, the resistance sends a reprogrammed T-800 (Arnold Schwarzenegger)—the same model that was the villain in the first film.