[The event is indicated on Table 7.1 of the book under the family category.] (https://pbs.twimg.com/media/DXMHdtpXUAAD0N_.jpg) The book itself didn't expand on this particular event and I wasn't able to discover much information that would've given me more insight into this, so would this mean that this is a relatively new discovery?
Additionally, searching the Chinese web in Baidu/Wenku didn't yield the right results as well, but that's probably cause my search terms needs more refinement. The final search term I used roughly translates to Ancient Chinese History the Only Time a Concubine Murdered an Emperor (中国古代历史上惟一次妾谋杀皇帝).
Thanks in advance.
Most likely Emperor Xiaowu of Jin, who was killed by his consort after he called her too old. Emperor Zhongzong of Tang was also commonly believed to be killed by his wife, but she was the Empress and not a concubine.