Off the official site:

At the end of "Terminator 2: Judgment Day," Sarah vanquished the
liquid metal Terminator sent from the future to kill her teenage son,
John. Sarah and John now find themselves alone in a very dangerous,
complicated world. Fugitives from the law, they are confronted with
the reality that still more enemies from the future, and the present,
could attack at any moment.

THE SARAH CONNOR CHRONICLES reveals what happens when SARAH (Lena
Headey, "The Brothers Grimm," "300") stops running and goes on the
offensive against an ever-evolving technological enemy bent on
destroying her life, and perhaps the world. Her son, 15-year-old JOHN
CONNOR (Thomas Dekker, "Heroes"), knows that he may be the future
savior of mankind, but is not yet ready to take on the mantle of
leadership that he's told is his destiny. John finds himself
inextricably drawn to CAMERON (Summer Glau, "Serenity," "The Unit"),
an enigmatic and otherworldly student at his high school, who soon
proves to be much more than his confidante – she assumes the role of
Sarah and John's fearless protector. On their trail are not only
threats from the future, but an intelligent and tough FBI agent,
JAMES ELLISON (Richard T. Jones, "Judging Amy"), who soon becomes a
powerful ally.

Directed by David Nutter and produced by Warner Bros. Television and
C-2 Pictures, THE SARAH CONNOR CHRONICLES represents an exciting
reinvention of the "Terminator" franchise, in which the strong and
intrepid Sarah discovers that protecting her son and stopping the
rise of the machines is more difficult than she had ever imagined.