When Lin Wan stepped into the gloomy and old dormitory 404 of Jiangzhou University, she thought it was just the beginning of escaping from her oppressive family. However, the wordless black diary under the bed dragged her and her three roommates into a nightmare from which they could not wake up.
The bloody rules revealed in the diary have become their only survival guide - don't look for the source of the sound of water in the middle of the night, don't respond to whispers outside the door, don't stare at the strange shadow in the mirror... Violation will result in death.
Rules are constantly being added, and supernatural events are escalating. A life-threatening figure wearing red shoes lingers outside the door, the endless terrifying corridor is reflected in the mirror, and the dark red water stains oozing from the floor condense and form... Su Ya, a sports student, Chen Xue, a medical student, and Su Xue, an occult enthusiast, four girls with very different personalities are forced to form a fragile survival alliance. They discovered that the entire dormitory building was actually built on the ancient "Yin Ruins", and they were just a new round of "sacrifice" in the curse cycle.
Dealing with evil spirits again and again, with their lives hanging on a thread, they explore the source of the curse. Su Xue sacrificed the amulet left by her sister to temporarily suppress the seductive diary, but it also attracted a more ferocious counterattack. When the door of the dormitory was about to be broken down and the evil thing in the room was about to take shape, the diary revealed the cruelest truth: the key "core" to break the situation was hidden among the four of them.
Suspicion and fear spread among the survivors. Who is the "ghost" left over from the last cycle? Is that diary that records rules and craves blood a life-saving straw or a soul-eating trap? When the Yin Shi bell rings, can they find the real "core" in their mutual suspicion and break this never-ending cycle of death?
