A string of murders and kidnappings strikes Longjiang City. Each victim is left with a postcard bearing part of a constellation on the back and the words "To Luo Lin" on the front. Luo Lin, GDA's regional agent general for Asia, receives a challenge from "Jie," the opponent who forfeited a competition seven years ago, and is forced to accept. With help from Li Er, captain of the criminal investigation team at the Longjiang Public Security Bureau, Luo Lin joins forces with Cheng Feng, a village doctor living in Pelican Town, to investigate.
As the clues to the twelve zodiac signs gradually come together, an old school case from seven years ago comes to light. All the victims were connected to it: sixteen-year-old Zhang Xiaozheng was accused of pushing editor Ma Weidong into a lake, where he drowned. After being sentenced to life in prison, Zhang Xiaozheng died behind bars. His father, Zhang Yanjie, acting under the name "Jie," seeks revenge on everyone who helped fan the flames back then.
As the truth is peeled back layer by layer, the underground maze of the Twelve Zodiac Palaces reveals six star gates, six keys, and a father's obsession with his son that transcends life and death. The final confrontation is not only a battle of wits, but also a judgment on truth, justice, and love. And the ultimate truth revealed by The Book Within the Book, The Innocent Prisoner, hidden behind every puzzle, catches everyone completely off guard.
