In the future, an advanced artificial intelligence known as Skynet wages war against humanity. To eliminate the leader of the human resistance, John Connor, Skynet sends a new, more advanced terminator, the T-1000, back in time to kill John as a child. To counter this threat, the resistance captures and reprograms a T-800 model terminator to serve as John's protector. The T-800 is sent back in time to the present day, where John is a rebellious young boy living with foster parents, unaware of his destiny.

The T-1000, a shape-shifting liquid metal robot, assumes the identity of a police officer and begins its relentless search for John. Meanwhile, John's mother, Sarah, who has been preparing for the impending apocalypse foretold by the first terminator, is held in a mental institution after attempting to bomb a computer factory to prevent Skynet's creation. Sarah has become a hardened warrior but is deemed delusional by society. The T-800 finds John first and the two form an unlikely alliance. With the common goal of keeping John alive, they plan to break Sarah out of the institution. Together, the trio must find a way to stop Skynet from ever being invented, all while being pursued by the seemingly unstoppable T-1000.