Decades after the sentient artificial intelligence Skynet took control of the planet in 2022, the resistance is still fighting against the machines. Following a fierce battle, Eiko, a guerilla soldier in Japan, manages to corner a Terminator—Skynet's elite killing cyborg. Eiko extracts crucial details of its plan, allowing the resistance to send her back in time and secure a different future.

In August 1997, days before Skynet's looming nuclear attack known as Judgment Day, Malcolm Lee works on launching Kokoro, a new AI model designed to fight for humanity. As Judgement Day approaches, a Terminator arrives in Japan to hunt Malcolm and his children before Kokoro becomes self-aware. Malcolm must prevent his creation from getting misaligned and coming to the same conclusion as Skynet: the extinction of humans.