Human Resistance leader John Connor (Jason Clarke) launches a final offensive against Skynet, an artificial general intelligence system seeking to eliminate the human race, in 2029. Before the Resistance can triumph, Skynet activates a time machine and sends a T-800 (Model 101) Terminator back to May 12, 1984 to kill John’s mother Sarah (Emilia Clarke). John’s right-hand man, Kyle Reese (Jai Courtney), volunteers to travel back in time to protect her. As Kyle floats in the machine’s magnetic field, he sees John being attacked by another Resistance soldier (Matt Smith) and has visions from his childhood about Sarah Connor from 2017.
When it arrives in Los Angeles 1984, Skynet’s T-800 is disabled by Sarah and its reprogrammed doppelgänger sent to protect her when she was nine years old, nicknamed “Pops” (Arnold Schwarzenegger). Kyle arrives a short time later, and is intercepted by a T-1000 (Lee Byung-hun). Sarah and Pops join Kyle and destroy the T-1000 with acid; she and Pops reveal that they have constructed a makeshift time machine similar to Skynet’s, and Sarah plans to travel to 1997 (the year Skynet becomes self-aware). Realizing that the timeline has been altered, Kyle is convinced that the future has changed because of the warning he received in his childhood vision and persuades Sarah to travel to 2017 to stop Skynet.
Kyle and Sarah arrive on August 28, 2017, materialize in the middle of a busy San Francisco highway and are apprehended by city police. While they are treated for injuries, Sarah and Kyle learn that Skynet is called “Genisys” (a soon-to-be-unveiled global operating system which is embraced by the public). John suddenly appears and rescues Sarah and Kyle; Pops arrives and unexpectedly shoots John, revealing that John is an advanced T-3000 Terminator. While Kyle was traveling back in time a T-5000 (Smith), the physical embodiment of Skynet disguised as a member of the Resistance, attacked John and transformed him into a nanocyte infiltrator. John, tasked with ensuring Cyberdyne Systems’ survival, traveled back in time to assist them with the development of Genisys and thus safeguarding Skynet and its machines’ rise.