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.

Sarah visits Miles Dyson's widow to find the creator of Skynet. She leads her to a man named Andy Goode who used to work with Dyson and is building a chess-playing computer named "The Turk." John and Cameron try their best to fit in on their first day at a new high school.

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.

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.