"The TV series "The Oath" is directed by Mao Weining. The main plot tells the story of Yan Shaobai, a mathematical genius who bears family hatred and hates the Japanese invaders during the Anti-Japanese War. By chance, he meets the officer Xiao Siyu and the gangster Lei Hu, and they form brothers with different surnames. During a battle, Xiao Siyu's head was hit by shrapnel, which affected his ability as a "war chess player"..."