Story : Jack and Katie's relationship progresses, while Courtney's comes to a screeching halt after Jack discovers Nate is cheating on her with another girl. When Bobby is required to do a family history project for class, he goes through his mother's closet for clues about his family and discovers a letter that reveals the real reason his father left. Meanwhile, Grace is shocked to learn that her affair with Tom has cost her more then she had bargained for.