Kelly Collins (Hilary Duff), is a free-spirited eighth grade girl whose mother gets married to Brigadier General Joe "Sir" Maxwell (Gary Cole). When her new stepfather becomes the Commandant of a Military academy, George Washington Military Academy, Kelly and her family move upstate. Kelly has to enroll at the school, since it is the only school in the area, leaving behind her art school and her best friend Amanda (Sarah Gadon). On her first day at military school, she befriends Carla (Andrea Lewis), a girl who has been there for a long time and shows her the ropes. Kelly, at first, has trouble fitting in and obeying the orders of the officers above her, especially Cadet Captain Jennifer Stone (Christy Carlson Romano), who has a crush on Cadet Major Brad Rigby (Shawn Ashmore). Kelly feels drawn to Brad instantly, and competes with Captain Stone for his attention. Captain Stone does not treat Kelly well, verbally abusing her and destroying her personal belongings. After taking a long time to complete the obstacle course, Captain Stone has Kelly take the course again. After getting all dirty from the course and finishing it, Kelly heads to the dance, but stumbles and ruins Captain Stone's dress at the dance. Her stepfather talks to Kelly in his office about the incident and what the teachers are saying about her. At home, Kelly is ready to tell her mom about her feelings and opinions of the new school, but before she could even start, her mother reveals to her that Kelly is going to have a half-sibling (implying that her mother and her stepfather are going to have a baby together). Seeing that her mom needs her support, she vows to help her stepfather learn how to take care of a child and make him "ready" to be a dad. To get back at Captain Stone for destroying one of Kelly's $15,000 blanket, Kelly decides to paint into Stone's hair in the middle of the night, in the same pattern as a blanket of Kelly's that Stone ruined.