The story takes place 10 years after "Terminator 2", and the Terminator is back. John Connor (played by Nick Stahl) is 22 years old at this time. After his mother died, he lived an anonymous life and was unwilling to face the upcoming fate. However, fate does not depend on his will. After two failures, "Skynet" sent a more advanced TX Terminator (played by Kristanna Loken) to hunt him down, and humans also sent back the improved Terminator T-850 (played by Arnold Schwarzenegger) of T-800 to protect John. John happened to meet his childhood friend, veterinarian Kate Brewster (played by Claire Danes). Kate's father is the head of the US military's "Skynet" system. She herself will become the deputy commander of the human rebels and naturally become the target of TX. Under the protection of T-850, the two began their escape. At the same time, the US computer system was invaded by a virus, and humans were helpless and prepared to activate "Skynet". Once "Skynet" took over the US military defense system, humans would be the first to be eliminated. Faced with the future that has already happened, John Connor and Kate Brewster decided to rise up in resistance. With the help of T-850, they will once again change the destiny of mankind.