The No. 3 Psychiatric Hospital of Linyuan City has three strict rules - after 12 midnight, it is forbidden to wander in the corridor on the fourth floor; At night, it is forbidden to recall all kinds of strange stories about the hospital; No one should be trusted, no matter what the danger is. Those who violate these three rules will see the abyss. Jian Huai is a psychiatrist who has worked in the hospital for many years and knows these rules well. However, the appearance of the long wind shattered this calm. He is a new patient, with a gentle appearance but deep eyes, as if he is hiding a secret that no one knows. The two gradually intersected at work, and Jian Huai began to notice some strange phenomena on Changfeng's body. Late one night, Jian Huai violated his principles and wandered the corridors, trying to unravel the mystery of Chang Feng's body. Just as he was immersed in the memories of the strange talk about the hospital, he suddenly saw an abyss-like scene. This made him realize that maybe he shouldn't have completely rejected the words of the patients, and maybe there was a hidden story behind them. At the same time, Long Wind seems to be looking for something, and his behavior is getting more and more erratic. Jian Huai began to wonder if this seemingly ordinary patient was really as simple as it seemed. The relationship between the two is also complicated by these mysterious events. In the end, in a late-night corridor, Jian Huai and Changfeng faced the abyss together and uncovered the secrets hidden behind the hospital. It turns out that the patients here all have their own stories and there is a connection between them. Through each other's help and support, they not only solved the mystery, but also found inner peace and redemption.