The primary subject of the episode is the period after middle school graduation of Zack & Cody Martin. Zack didn't graduate, and has to spend the summer in summer school, while Cody has a job at a local Revolutionary-war themed grocery store. It also contains Maddie volunteering as a Counselor-in-Training at a Catholic camp for troubled girls, which turns out to be a dump. And this season, it's her temporary replacement that stands out as much as the show has for the past two and a half years; A young girl named Millicent played by a slightly older young woman named Kara Taitz.
The only disappointment is that she wasn't used as often during the third and final season. Incidentally, Zack meets a girl in summer school played by Tara Lynne Barr, who's apparently as much of a nervous wreck as Millicent. Hopefully, we'll see more of her in the future.