During the summer vacation, Lin Yan took his friends Jiang Xun and Xie Qingyue back to his grandfather's house in the countryside. The old man repeatedly warned: "Never go near the locked room on the third floor."
The more forbidden it is, the more curiosity grows. While grandpa was out, the three of them pried open the door, only to find that it was just an ordinary study room filled with old books.
The moment Lin Yan casually picked up the book, the mechanism was triggered - the room collapsed into a closed chamber, drawing them into a different world intertwined with science fiction and magic.
Floating city, elemental mages, mechanical guards... Grandpa Lin Shoushan cannot enter and can only send messages across time and space for remote guidance.
They broke through the desperate situation, stood side by side in life and death, and finally passed the "81 difficulties" and returned to reality.
When the door was locked again, the crystal from another world in his pocket was burning hot.
They know that once that door is opened, it can never be closed.
Mission: Curiosity and courage are the keys to exploring the unknown, companionship and protection are the power to overcome difficulties