Luke Malloy and his friends, A.J. and Riley, perform together as a band named Steel Monkey. They are starting middle school in two days, warned by Luke's older sister Diana of the dangers of junior high, and intimidated by the looming presence of the bully, Meat, who constantly threatens incoming sixth graders. The next day, Steel Money are booked to perform at a carnival talent show. Luke embarrasses himself in front of his crush, Alice, and the boys encounter Meat and his friends, who threaten them. Feeling his start of middle school is tainted, Luke wishes it could remain the last day of summer, and immediately afterwards it seems the effects of a head injury grant his wish! Finding himself stuck on the same day repeatedly, Luke finds that the only way to move on with his life is to regain his confidence that middle school will start on a high note.