Handsome, brave, clever and charismatic, Bai Yutang is the youngest sworn brother and the best fighter of the "Five Rats", whose other members are Lu Fang, Han Zhang, Xu Qing, and Jiang Ping.

After fellow knight-errant Zhan Zhao receives the title "Imperial Cat" from the emperor, Bai Yutang becomes jealous and hurries off to the capital Kaifeng to challenge him.

The emperor forgives his many crimes and assigns him to assist his sworn brother Judge Yan Chasan (顏查散) to foil Prince of Xiangyang's (襄陽王) rebellion.

Overconfident in his abilities, Bai heedlessly ventures into the prince's deadly Sky-Scraping Tower and suffers a tragic death in the Brass Net Trap.

Significantly younger than all the other heroes and gallants in the book except for Ai Hu, Bai is the first one to die when he falls in the Brass Net Trap of the Sky-Scraping Tower.