Over ten years after Jenny Shepard (Lauren Holly) destroyed the original Terminator that was programmed to kill her, two men arrive in Washington D.C. from the year 2029. The first is a Terminator (Mark Harmon) identical to the one that Jenny first encountered, while the second is an unknown man (Michael Weatherly). The target: Jenny's illegitimate daughter Abby (Pauley Perrette).
In the fifth-season finale, the agents are all at risk as they search for a killer who took the life of one of their own.