On a rainy night in Ivy Lane, the secret room in the west wing of Shen's house hides a terrible secret. The eldest daughter of the Shen family, Shen Zhiyi, knelt down in front of the murder case in a strange posture. Her left leg was missing, half of a Tai Chi diagram was painted on the cinnabar on her calf, and the thin mark on her neck was like a hairline. When forensic doctor Gu Qiuyu brushed the red rope around the deceased's wrist with his fingertips, he found that it was exactly the same as the unsolved "red rope case" three years ago - the same sense of ritual, the same missing body parts, the same jade earrings.
Criminal police captain Mo Ziqing opened the secret door of the secret room, and six blood-stained earrings and a white bone were clearly visible on the mahogany table. The sacral carvings matched Shen Zhiyi's cinnabar diagram to form a complete Tai Chi. The old housekeeper drowned in the fish pond, holding the seventh earring tightly in his hand. The old tape recorder played a creepy nursery rhyme in a loop: "Seven girls picked lotus pods, but they lost their left legs and couldn't find them..."
The seven girls from the "Seven Skills Club" ten years ago are now dying one after another in a sacrificial manner. Gu Qiuyu caught a glimpse of a mysterious figure with a mole at the end of his left eye in the flames of an oil painting, gradually overlapping with the face in the yellowed photo in his wallet; Mo Ziqing traced the murder case of a female college student who lost her hand three years ago, and found that the clues always lead back to the wealthy door of Shen's house that is full of topsy-turvy gossip.
When the anonymous text message sent a photo of the seventh vacant seat, Gu Qiuyu's name was clearly listed. The red rope is not only wrapped around the wrist bones of the deceased, but also the grudges and conspiracies spanning ten years. They must uncover the secret of the Tai Chi remnants before the remaining five people are killed - is the murderer completing the bloody ritual, or has the dead already laid out a self-destructive chess game?
