15-year-old Louise Tuckerman has Ace, an M4A3E8 Sherman, in her basement, belonging to her grandfather, who was its commander back in World War 2. With him now passed on, the medium tank was discovered by officials, and excitement ran rampant in the once-quiet town. With the threat of Ace being sent off and made inoperable in a museum, the young girl was given a rare, unexpected offer; "sell" the tank to a well-known Japanese high school, transfer as a student there herself and join Saunders tankery team. With a strong desire to participate in her favorite sport, which was illegal in Europe, her answer to that is obvious.