In the winter of 2041, Lu Shiqian, a forensic medicine student, picked up a barefoot girl on a snowy night. She is nameless, has the mind of a child, the silver bell on her ankle jingles, and her body temperature is so low that snow does not melt on her skin.
At the same time, 17-year-old Qi Guanjiu was dealing with a bizarre elevator murder case. He belongs to a secret organization called "Blue Flame", which specializes in eliminating invisible existences called "double spirits" - they attach themselves to humans and eat away at the host's consciousness until the body collapses.
The two lines intersect in the explosion ruins of an underground laboratory. That girl was once the experimental subject numbered N-0130. Her consciousness was fused with the core fragment of the heavy spirit. She was both a person and a key. The doctor in the laboratory is still alive, hiding in the darkroom of the abandoned warehouse, holding the last set of data about the truth about the heavy spirit in his hand.
Zhong Ao, who adopted Qi Guanjiu ten years ago, knew about the existence of this project from the beginning. The founding of Lan Yan, the laboratory of Qi Guanjiu's parents, the deliberately implanted virus - the layers of secrets are being loosened with the appearance of Ye Xue.
When the three parties of the police, Lan Yan, and the remaining forces in the laboratory competed, Qi Guanjiu had to shoulder the real responsibility under the shell of idleness. He wants to find out what the heavy spirit is, protect Ye Xue, and face the iceberg behind Zhong Ao. And the silver bell on Ye Xue's ankle was ringing more frequently day by day.
