He went MIA during a mission, and ended up in Lu Bu's camp. Manipulated by Lu Bu to assassinate Cao Cao in accordance with Pang Tong's scheme, Xiao Meng, together with Liaoyuan Huo, unwittingly brought about the Sima clan's demise at the hands of Cao Cao. Desperate for vengeance, he aided Lu Bu in resistance to Cao Cao's Xuzhou campaign, and when Lu Bu failed, proceeded to again make an attempt on Cao Cao's life. Due to Sima Yi's betrayal, he failed and was subjected to a brutal execution, but a glimpse of foresight at Sima Yi's long-term sheme just before dying allows him to rest in peace. However, his death greatly aggravated Liaoyuan Huo, and despite his wish, enlarged the rift between him and Sima Yi.