In the Western Market of Chang'an during the Great Tang dynasty, a bizarre murder case occurred. Seven literati of Chenhuidwell died silently overnight. The deceased had peaceful facial expressions and no traces of external injuries. The scene yielded no ordinary poisons or signs of a struggle, making it an unsolved and traceless mysterious case. Xie Yanci, the patrol defense chief, was at his wits' end. Hearing that Su Wanqing, the proprietress of Ningxiang Shop, was exceptionally talented and well-versed in the pharmacology of spices throughout the world, he went to her door to seek help. Relying on her extraordinary fragrance-identification skills, Su Wanqing sniffed out the lethal secret fragrance "Lone Mist Sinking Frost" and followed the traces of the spice ingredients to peel back the layers. Tracing the clues together, the two cleared away the mist, uncovered the grievances behind the old case of Nanshan Academy five years ago, and ferreted out Wen Jingran, the true culprit consumed by obsession and seeking revenge through fragrance.