An old man living alone died in a locked home. There were no signs of external intrusion at the scene, and it was initially determined to be an accident. Through the "daily fixed flower watering time" in the old man's diary, Lin Yan discovered that the window latch had slight wear and tear, and combined with the neighbor's testimony, he identified the old man's distant nephew (to create a secret room for inheriting the property, and used the old man's habit of opening the window when watering the flowers to arrange the mechanism in advance).
