Wu Song takes advantage of a letter he obtained at the Centipede Hill, in which the brigand chief of Twin Dragon Peak, Wang Feitian, asked the Centipede Hill bandit leader, Wu Qian, for his assistance. Disguising himself as the second-in-command bandit leader, Li Er the Mendicant Monk, Wu Song leads Zhang Qing, newly arrived from Crossways Rise, together with Shi En and two of his attendants to Twin Dragon Peak. They prepare to strike from both within and without, and wipe out Wang Feitian.
武松利用在蜈蚣嶺得到的一封二龍山寨主王飛天給蜈蚣嶺寨主吳千的求援書信，扮裝二寨主李二頭陀，帶領剛從十字坡來的張青、施恩和兩個孩子，作爲隨從奔二龍山，準備裏應外合，消滅王飛天。