In late autumn in Nancheng, it rains continuously.
Su Wan, a cold and solitary organizer in the archives, lost her best friend Lin Xi three years ago. The girl disappeared inexplicably in an old alley, and the case was hastily sealed and became an unsolved case.
Three years later, a high school sophomore girl from Mingde Middle School fell from a building late at night. It looked like she had committed suicide, but her falling posture secretly coincided with her disappearance that year. The dusty darkness was suddenly torn open.
Su Wan, a top student in psychological profiling at the former police academy, met the calm and decisive criminal investigation deputy captain Lu Yanci, and the two teamed up to investigate.
A case of falling from a building led him to drowning in a secret room, and a series of seemingly unrelated accidental deaths were peeled off layer by layer, and they were all intertwined with an old case of campus bullying and falling off a cliff twenty years ago.
A replica of a bone-shaped pendant, a diary dusted in despair, old bones buried deep at the bottom of the cliff, shadows constantly emerging from the darkness...
