Sarah and John have been in the same place for a couple of years.  When the man that Sarah is with proposes to her, she decides that it is time to move on.  When he goes to the police, the FBI become involved and he learns some things about his would-be fiancé.  Meanwhile, John is trying to fit in to a new school and a girl named Cameron tries to be his friend.  Since they didn't change their aliases on this move, the FBI now know about them and so does a Terminator who pays the school a visit as a substitute teacher.  John escapes with his life with Cameron's help, who happens to be a machine also.  Later John convinces Sarah to try and put a stop to Skynet which still goes online despite Myles Dyson's death.  When she agrees, Cameron takes them into the future to the year 2007 in order to do so.