Shi Ren was from Guangyang Commandery (廣陽郡), which is located southwest of present-day Daxing District, Beijing.
Shi Ren and Mi Fang allowed Sun Quan's forces to overrun Jing Province, leading to Guan Yu's defeat and death.
In the novel, before the Battle of Fancheng, Guan Yu appoints Mi Fang and Fu Shiren as the commanders of the vanguard force, but that night they carelessly allow a fire to break out in the camp.
Although Mi Fang is initially reluctant to do so, he defects to the enemy as well after he hears that a threat from Guan Yu to execute him if he fails to deliver supplies to the frontline in time.
They overhear a plot to kill them, so they assassinate Ma Zhong (馬忠), who captured Guan Yu in an ambush, and bring his head along when attempting to return to Liu Bei's side.