After transmigrating into a book, Shen Zhiyi wakes up from her own mourning hall coffin, discovering she has become the Marquis's wife destined to die early in the original plot. To survive, she relies on her memory to avoid death traps such as the calming soup and ancestral hall tea cups. She and Pei Yan, the Marquis of Zhenbei, go from distant spouses to allies investigating cases side by side. Following knots, old medicines, jade hairpins, and tea cups, the two reinvestigate past events and uncover the truth behind Su Wanning's years of instigating misunderstandings and manipulating situations. Shen Zhiyi is no longer bound by the identity of the vicious female supporting character, Pei Yan sees her true nature clearly, and Su Wanning finally confesses to deliberately driving the deadly trap and leaves the Marquis's estate.