A male body was found at a construction site on the outskirts of the city. The time of death was locked at three in the morning. The only witness, Su Wan, said that he "saw a man in a black trench coat leaving the scene." Lu Chen was in charge of the case, but found that Su Wan's testimony was full of loopholes, and that she had a secret connection with the victim of the unsolved case three years ago. As the investigation deepens, the library at three in the morning, the vague dreams in Su Wan's diary, and the old clues left by Lu Chen's partner gradually intertwine, and the two are forced to explore the truth together. When more "three o'clock anomalies" emerge, they realize that the identity of the witness is just a disguise, and the real secret is hidden in the cracks of memory at midnight.
