The story starts in the year 2032 with a squad of Tech-Com soldiers storming a Skynet facility in order to stop a T-X from entering a time displacement machine. However, they are no match for the T-X's superior capabilities and all are gruesomely killed.
Meanwhile, Katherine Brewster and the Human Resistance ambush the T-850 that was responsible for the death of John Connor. A Tech-Com technician reprograms the cyborg to be sent back to July 23, 2003 to protect Kate and John's earlier selves. The T-850, with the assistance of several Tech-Com soldiers manages to fight its way to the main gate of the Skynet bunker and it enters the time displacement machine.