Chuck learns more about Sarah's past when they run into her old high school nemesis Heather Chandler. Sarah's teenage insecurities come to surface and she tries to avoid Heather at all costs. Chuck, on the other hand, does everything he can to hear more about Sarah's hidden life. When Heather's nerdy husband Mark turns out to be a key player in a new mission, the agents must attend Sarah's high school reunion to prevent the sale of potentially dangerous super-bomber plans -- all the action ends with the ultimate cat fight. Meanwhile, Big Mike leaves town for a day and Buy More's new assistant manager Lester decides to implement a new sales policy.