Fate is changed forever on the explosive season finale episode! The Connors come face-to-face with Weaver in a confrontation that shakes John to the core and changes his reality. Nothing will be the same.

Sarah finds herself in a business transaction with a mysterious business man named Sarkissian, who claims to be in possession of the stolen Turk computer system and wants an exorbitant amount of money for it. Derek recalls his childhood before the so-called Judgement Day in 2011, when a nuclear war triggered by Skynet will destroy the world. Agent Ellison finally discovers that the terminator Cromartie is impersonating an FBI agent, and makes arrangements to apprehend him.

Cromartie kidnaps Sarah and races to Mexico to find John. When Derek, Cameron and Ellison discover what has happened, they come to their defense, which leads to one final deadly confrontation with Cromartie.

Cameron learns that a terminator was accidentally sent back to 1920s Los Angeles, and she tries to find out what happened to him. Meanwhile, John has a run-in with a group of punks while taking Riley home from a party.

When John attempts to rescue Skynet’s latest target he finds himself closing in on Weaver, but at what cost? Game plans change, causing Sarah and Ellison to reunite. Meanwhile, Weaver learns Ellison’s secrets.

Jesse's submarine mission in the future takes a fatal turn with unforeseen consequences. Back in the present, her plan to turn John against Cameron backfires when John discovers that Jesse--not Cameron--killed Riley and he makes a life-or-death decision.

After the Jeep explosion, John's 16th birthday makes him confront the fact that he's destined to be alone. Meanwhile, after Cromartie's massacre, Agent Ellison must face off against both the Feds and his faith.

Sarah breaks into Agent Ellison's apartment and discovers a file on her from her time at the mental hospital, leading her to Dr. Silberman, now a doomsday convert. Meanwhile Cameron signs up for a ballet class and John finds out how his mom escaped the mental hospital.

The Connors find themselves on high alert and in odd company after their house is robbed. A Terminator terrorizes Ellison, while another gets dangerously close to John Connor. Derek and Jesse continue to get reacquainted.

Sarah suspects that something fishy is going on at the medical clinic where she is being treated for insomnia. During her stay, she has flashbacks to a run-in she had with a man from the plant whom she thought she had already killed.

Sarah turns to a UFO convention for answers about the "three dots," more details about Riley's mission are revealed, and Ellison begins working with Catherine Weaver's AI prototype, "John Henry."

Sarah makes contact with an old friend to ask a favor, while John decides to pay a visit to Sarah's ex and Cameron makes a new friend. Together they infiltrate a resistance safe house and discover they are not alone. Meanwhile, Agent Ellison realizes that Sarah is still alive and a dangerous person from Sarah's past is reawakened.

Terminators come after a family whose unborn daughter plays an important role in the war against the Machines, and Sarah, Cameron, and Derek try to protect them.

While fighting to stay alive, Sarah is guided by the image of John's father. Weaver's attempt to protect John Henry has deadly consequences.

The Connors visit a town connected to the destroyed factory; Weaver sends a man into town in search of a survivor.

While Derek does surveillance on a lawyer he suspects may be connected to Skynet, Sarah and Cameron begin to have doubts about Riley.

Sarah's quest to find the meaning behind the "three dots" leads to a technology firm seeking an advanced microchip. Meanwhile, Jesse comes clean to Derek about her mission and Weaver makes an important introduction.

Sarah and Cameron investigate a nuclear power plant; John grows less enthusiastic about academics but flourishes socially with the help of a new friend; Catherine Weaver gets another piece of the puzzle for her pet project.