Meng Xingci, a 20-year-old archival intern, touches a stone that can cry. From that moment on, a pale blue-green mark of evil appears on the back of her hand, and she gains a power she should never have had: she can swallow evil objects that harm people. She is brought into the Zhenwu Bureau, an organization no one believes exists, where she investigates cases alongside Gu Lin, a cold-faced investigator, and Bai Xiaoman, who has an exceptionally keen sense of smell. Yet at the end of every case, they encounter the shadow of the same sinister cult, the Fate-Swapping Society. Its members intend to gather nine life candles and light the Guiding Fate Candle to exchange the lives of everyone in Linjiang City at once. Only later does Meng Xingci discover that she is the one and only person capable of lighting that candle.