Due to a genetic mutation, of the two brothers, the younger brother grew up with an unusually high body temperature and possesses ice powers, while the older brother possesses the fire system. The older brother is trained to be a powerful assassin by the Japanese who adopted him, while a mysterious organization in China is also in touch with the younger brother. The older brother is ordered to abduct the younger brother's lover, and when they meet again they become enemies, and during the fight the older brother recognizes the younger brother, Xiaoyu. After all they have been through, the two brothers eventually recognize each other and join forces to defeat the enemy.