The protagonist Cheng Mo, a history teacher in an ordinary middle school, fell into long-term insomnia and auditory hallucinations because he witnessed a student drowning three years ago. His mother died young, and his father was a brain science professor who was discredited for academic fraud, leaving half of his burned manuscript "The Abyss of Consciousness" behind. Cheng Mo used the music box left by his wife to soothe his nerves every night, until one rainy night, he accidentally discovered that the microchip at the bottom of the music box could scan his brain waves caused by hallucinations and materialize them into "memory fragments" from three hundred years ago.
