At four o'clock in the morning, half of the world's population disappears in their sleep.
No sign, no explanation. Only patches of gray-blue fog quietly covered the oceans, coastlines, and every major river. People who enter the fog zone never come back.
When Lu Zhiyi woke up, her grandmother was gone, and so was her seven-year-old sister.
The next day, she and six of her classmates stood on the bank of the Yangtze River in Yuzhong District, Chongqing. They all have one thing in common: the most important person disappears into the fog. They all also received the same temptation - a mysterious creature possessed by a cat told them that the end of the fog is the "other world", where all the disappeared people are.
As long as you recite the right spell, you can get in.
What they don't know is that the first group of people who disappeared have spent an unimaginable long time in the other world, and most of them have been homogenized into monsters, elves, and fairies. They don't know that if they stay in the other world for more than seven days, they will never be able to return. They don't know that the cat that bewitched them is just a chess piece.
All they knew was that the person they were looking for was inside.
The entrance to the other world is just above the fog-shrouded water.
Concept: Celtic mythology