In a Chinese village during the Qing Dynasty, a crippled man named Tian Haoli helps the poor and illiterate navigate the intricacies of the yamen courts in exchange for food, essentially functioning as a lawyer. He dreams of the Monkey King, a trickster demon, and by day seeks the Monkey King's advice when he must scheme his way out of trouble in court - for example, sneakily modifying a character on a contract to free an innocent client, Li Xiaoyi, from her brother-in-law's attempt to steal her land.

A week later, Xiaoyi begs Tian for help once more, and he goes to her hut to find her brother Xiaojing there, wounded. Xiaojing is a wanted man, pursued by the ruling Manchus' unstoppable Blood Drops. He is also innocent, having been exiled ten years ago when his master fell afoul of the Manchus for writing something the Emperor's legal team interpreted as seditious. Xiaojing says he doesn't want Tian to save him, but rather to save his master's book, which he has spent the last ten years protecting. The book is a vivid account of a terrible massacre committed by the Manchus - a massacre they claim never happened. Terrified of drawing the attention of the Blood Drops, Tian tells Xiaojing that he cannot help him.

Later, the Monkey King appears to Tian and tells him that if he doesn't help reveal the truth of the massacre, he is complicit in it. So Tian arranges safe passage for Xiaoyi and Xiaojing to Japan, where they will be safe. Tian cannot accompany them as his old injury will only slow him down. A few days later, he is arrested by the Blood Drops and charged with aiding traitors and reading a forbidden book. He uses his usual clever arguments in court, but the Blood Drops are far less bound by the strictures of the law than the usual judges. They torture Tian. To get through it, he talks with the Monkey King in his head, and the trickster god helps him tell tales that never reveal the whereabouts of the book.

On the eve of his execution, Tian ponders how to ensure the contents of the book survive even if the book itself never makes it to Japan. He creates rhymes based around the events of the massacre, utilising the Mandarin language's flexibility to code the truth into puns and approximations that hint at the truth, then shares them with the local children outside his jail cell window. The children pick up the rhymes immediately.

As he is executed, Tian asks the Monkey King if it was all for nothing, but the Monkey King tells him someday the book will return and clever scholars will see the truth embedded in the rhymes. The Monkey King bows to Tian as he dies a hero.