In a post-apocalyptic 2029, humanity is on the brink of annihilation by Skynet and its army of machines. The leader of the human resistance, John Connor, orchestrates a final push against the machines. When Skynet activates a time machine to alter history in its favor by targeting John's mother, Sarah Connor, in the past, John sends his loyal soldier, Kyle Reese, back to 1984 to protect her. Upon arrival, Kyle discovers that the timeline has been altered: Sarah is already a skilled fighter, aware of the future, and has been raised by a reprogrammed Terminator, whom she calls "Pops", since childhood.

As Kyle adapts to this new reality, he learns that Skynet's plan has changed as well, becoming more complex and threatening than ever before. The trio must navigate unforeseen events as they encounter advanced and deadly new enemies, while they form their resistance. With the aim to prevent Skynet from ever being created, they embark on a quest to find and destroy the roots of the artificial intelligence before it can implement its catastrophic judgment day. However, their journey is filled with challenges as they confront both the past and new potential futures, learning that their actions may create unexpected consequences.