Based on the heroine of the Terminator series of films, Sarah Connor (Lena Headey), The Sarah Connor Chronicles begins where Terminator 2: Judgment Day left off. Sarah had just vanquished the Terminator sent from the future to kill her son, John (Thomas Dekker). Now, Sarah and John are alone in a complex world as fugitives as they constantly look over their shoulders for more enemies from the past, present or future that could attack them at any time. Tired of running, Sarah opts to go on the offensive against the Terminators set on ending her life, as well as the world.

John knows that he may be the one to save mankind, but at only 15 years old, he's not ready to take on the responsibility of his destiny. John finds himself drawn to Cameron (Summer Glau), a fellow student at his high school, who becomes more than just a classmate when she becomes John and Sarah's protector. Trailing Sarah and John is FBI agent James Ellison (Richard T. Jones), who soon becomes an ally to the duo.

In an exciting extension of the Terminator film series, Sarah must learn how to not only protect her son from the evil they face, but protect the world from the rise of the ever-evolving Terminators.

The Second season marks the introduction of several new characters including John's new love interest Riley (Leven Rambin). And the CEO of Cyberdyne Catherine Weaver (Shirley Manson). Returning full time this season are Derek Reese (Brian Austin Green) and Cromartie (Garret Dillahunt). Fan favourite Charley Dixon (Dean Winters) also returns.