Greenbrook High School has an annual camp retreat where each class has the opportunity to get to know one another and embrace their school spirit. It's also where the X List is formed. Each year the senior boys make a list of girls and their mission is to complete whatever task goes along with that girl before time expires. Everyone in the class has a bet going on who will win the Hit Games. Hallie isn't the most popular girl in school, but she isn't invisible. Her twin brother, Hayden, is captain of the varsity soccer team and an active member of the HG. His only focus is playing soccer and winning the HG while Hallie tries to get into her dream school, Harvard. Senior year proves to be one of the most stressful times of both of their lives.