A change of pace in this week's episode. The story mainly focuses on what Cameron does during nights. (She "doesn't sleep".)
It turns out she has "befriended" a wheelchair-bound guy who works nights in some records office. He lets her in at night to do research in return for glazed donuts.
While there she spots a T-888 model in a photograph taken in the 1920s. Cameron does some research and discovers that the terminator arrived in the 1920s by mistake. His appearance inadvertently caused a speakeasy to burn down and a young architect died. The architect was supposed to design a particular building necessary to the terminator's plans so the machine has to become involved in building it himself!
After the building is completed the terminator disappears from history. Cameron figures it out and goes to the building. She has a flashback to the new years celebrations for 2010 (which obviously hasn't happened yet) and "sees" the Governor get assassinated. She finds the 1920s terminator behind a bricked-up wall clutching a tommy gun. She fights and defeats the other machine.
There are lots of unanswered questions in this eposode. Why do the terminators want the Governor killed? How does Cameron "remember" what happened? Was she there as well?
Along the way she casually mentions to her "friend" that his tumor has returned. The next night he's not at the records office and she quickly befriends his replacement by offering her the donuts.
The B story this week concerns John and Riley doing teenage stuff.