When a father driving with his two children is gunned down on the freeway, Megan is puzzled when she can't find a specific pattern to the suspect's behavior and goes to Charlie for some insight. But as additional freeway incidents occur, Don uncovers an unlikely clue that may lead them to the killer. Amita seeks Larry's advice on making the transition from graduate student to faculty member. Charlie becomes concerned when he learns that Larry has been sleeping on his couch and living in his office.