Xiagu Danxin is a wuxia novel by Liang Yusheng first published as a serial between 5 October 1967 and 20 June 1969 in the Hong Kong newspaper Sin Wan Pao (新晚報).

20 years ago, Jin Shiyi had retired from the jianghu (martial artists' community) and settled on a remote island with his wife, Gu Zhihua.

He saves and befriends Qin Yuanhao of the Wudang School; defeats the imperial guard commander Wen Daozhuang; foils an assassination attempt on his father's apprentice, Jiang Haitian; and becomes famous in the jianghu for his heroic deeds.

Shi Baidu, the chief of the Six Harmonies Gang, pledges allegiance to Safuding, a high-ranking Manchu aristocrat – much to the disapproval of his fellows in the jianghu who are opposed to the Qing government.

In the meantime, some jianghu lowlifes led by Yang Hao reestablish the Heavenly Demonic Cult in Li Nanxing's name and commit several atrocities.

In 1971, the novel was adapted into a Hong Kong film titled The Patriotic Knights, produced by Great Wall Movie Enterprises and directed by Chang Hsin-yen.