Wu Sansi
In 705, Wu Zetian was overthrown in a coup, and her son and crown prince Li Xian, formerly emperor, was restored to the throne (as Emperor Zhongzong). Around this time, Cui Shi became "Kaogong Yuanwai Lang" (考功員外郎), a low level official at the ministry of civil service affairs. Upon Emperor Zhongzong's restoration, initially, five officials who were instrumental in the coup that overthrew Wu Zetian and restored him, Zhang Jianzhi, Cui Xuanwei, Huan Yanfan, Jing Hui, and Yuan Shuji, were powerful chancellors, but Emperor Zhongzong's cousin (Wu Zetian's nephew) Wu Sansi the Prince of Dejing, who was also the lover of Emperor Zhongzong's wife Empress Wei, soon became a trusted and powerful advisor to Emperor Zhongzong. Huan and Jing feared what machinations Wu Sansi might have, and so tried to make Cui Shi an associate and have him keep an eye on Wu Sansi, but Cui Shi, realizing that Emperor Zhongzong trusted Wu Sansi and not the coup leaders, instead revealed the coup leaders' plans to Wu Sansi. Subsequently, he became a strategist for Wu Sansi, and at Wu Sansi's recommendation was made "Zhongshu Sheren" (中書舍人), a mid-level official at the legislative bureau (中書省). The coup leaders were subsequently, after accusations by Wu Sansi, all exiled to the Lingnan region in 706 with provisions that they would never be allowed to return to the capital Chang'an. However, Cui Shi warned Wu Sansi that if somehow they returned to the capital later, they would create problems for him, and that they should somehow be killed in exile. Wu Sansi agreed, and at Cui Shi's recommendation, commissioned Cui Shi's cousin Zhou Lizhen (周利貞) to visit the Lingnan region, ostensibly to review the region, but with instructions to kill the five coup leaders. When Zhou reached the region, Zhang and Cui Xuanwei had already died, and Zhou had Huan, Jing, and Yuan killed cruelly.