I want to know the answer to the following question:
Which person plotted to overthrew the regime of Empress Dowager Yan?
All the background I'm provided with is that "However, palace eunuch Sun Cheng (d. 132 AD) masterminded a successful overthrow of her regime to enthrone Emperor Shun of Han (r. 125–144 AD).". Is that enough to answer the question?
Answer: yes