On the day General Keane is hailed as a war hero, his 6-year-old son Joseph vows to become a mech pilot and return to Earth. Then an enemy attack kills Joseph's mother and severely injuries him. Amid the chaos, Paul, a gambler, switches Joseph with his son Joey. Sixteen years later, Joseph enters mech pilot trials and clashes with Joey. Unaware Joseph is his long-lost son, General Keane is manipulated by Joey into turning against him, pushing father and son further apart.
