Deep Rooted Tree

Torbok, a slave boy in the Sim On household, was a violent troublemaker even adults couldn't handle, with his only ally being Tam, a maid in the same household. The year was 1418, during the reign of King Sejong, Yi Do. ©SBS

The captured slaves of the Sim family attempt to escape, but are subdued by soldiers and slaughtered. Witnessing this scene, Lee Do rebels against his father, Lee Bang-won, for the first time to save Torbok, who has fled into the mountains. ©SBS

Facing his father's threats of force, Yi Do declares that governance through literature is his ideal and demands the establishment of the Hall of Literary Excellence as an institution to nurture young talent. That night, the secret society Milbon, once purged by Yi Bangwon, shows signs of renewed activity. ©SBS

Chung Dong-gwang fell to an arrow and entrusted Chung Gi-jun with Torbok's pouch, which had been switched with the "Secret Book of Mirbon." Four years later, Lee Bang-won passed away, and another twenty-odd years passed. Torbok, having distinguished himself in military service in the north, changed his name to Kang Che-yoon. ©SBS

Kang Chae-yoon launches an investigation into a murder case to gain an opportunity to approach Lee Do. Kang Chae-yoon learns from Kari-on, a commoner living in Bang Village and a master of autopsies, about the unique method used to kill Scholar Ho Dam. It was the fatal technique "Dry Drowning Skill" used by martial arts master Lee Bang-ji. ©SBS

Kang Chae-yun rescues Lady So-i, a lady-in-waiting to Prince Gwangpyeong, from the fire at the foundry. Though unable to speak, she possessed a photographic memory, remembering everything she saw. She was none other than Tam, Torbok's childhood friend. Meanwhile, four movable type characters spelling "丨口亡己" are discovered on Yun Pil's corpse. ©SBS

The type left by Yun Pil represented "secret books." Meanwhile, Kang Chae-yoon, suspecting that two factions-one aligned with the king and the other with the perpetrators-were involved in the series of incidents through the corpse theft case, spots a man wearing a bracelet with the same pattern as the masked man at the bookstore in Bang Village. ©SBS

Kang Chae-yoon narrowly fails to capture the masked man Yun Pyung. The next morning, the body of scholar Jang Seong-su is discovered in the palace pond, with words symbolizing the secret society Milbon found beneath him. Shocked that his comrades are falling one after another to Milbon's hands, Lee Do agonizes over whether his ideals were truly right. ©SBS

Lee Do assigns Kang Chae-yoon to investigate the secret book, knowing full well that Kang Chae-yoon's goal is to assassinate him. Meanwhile, Son Sam-mun and Park Pen-nyong, having uncovered the mystery of "Guna Miyok" left behind by Yun Pil, are finally informed by Lee Do of the full scope of the secret operation. ©SBS

At the time of the incident, Karyon was meeting with court lady Soy to receive secret orders from Lee Do, but this fact cannot be made public. Kang Chae-yoon scrambled to prove Karion's innocence from another angle, and his efforts paid off as the truth behind the blackmail incident came to light. ©SBS

Lee Do summons Karion to the back mountain where Sungkyunkwan scholars gather to commemorate Jeong Do-jeong, and they share a drink. With Karion's assistance, Lee Do performs a human dissection to explore the principles of phonation. ©SBS

A picture of a drawstring pouch with an unfinished character for "blessing" stitched onto it is posted around town. Hoping Torbok might still be alive, Soy heads to the designated location. Meanwhile, Milbon also springs into action to retrieve the "Book of Milbon," which has been swapped for the pouch. ©SBS

Kang Che-yun and So-yi finally confirm each other's presence. But Yoon Pyung's sword strikes, and to save Kang Che-yun, So-yi regains her voice. Lee Do sends them far away, but So-yi returns to Lee Do to complete the project of creating the alphabet. Meanwhile, Jeong Gijun, having retrieved the "Secret Book of Mirbon" from Kang Che-yun, solidifies the bonds of the Mirbon. ©SBS

Kang Che-yun draws his blade against Lee Do. Lee Do tries to persuade Kang Che-yun to become an examiner for the creation of the script, but Kang Che-yun resists, arguing that it would be no good for the common people to learn writing. Meanwhile, Jeong Gi-jun and the Milbon discover Lee Do's plan to create a script and publicly reveal this fact.©SBS

Kang Che-yoon rescues Soy and Prince Gwangpyeong, who had been abducted by Milbon. Unaware of this, Milbon posts a notice demanding that Lee Do abandon his creation of the new script if he wishes to spare Prince Gwangpyeong's life. Upon seeing this, Kang Che-yoon keeps Prince Gwangpyeong and the others imprisoned, intending to force Lee Do to choose between the script and his son's life. ©SBS

In front of Yi Do, Kang Che-yun pledges cooperation with the project to create a new script and the arrest of Jeong Gi-jun. Meanwhile, Milbon, learning that Kang Che-yun is plotting to assassinate the king, attempts to win him over as an ally. ©SBS

Lee Do's planned transaction is abruptly halted. Jung Gijun, realizing the terrifying power of the characters Lee Do created, resolves to obstruct their distribution with all his might. The next day, the civil service examination is held, but the top-ranked candidate who passes is a servant from Bang Village. ©SBS

Kang Chae-yun cherishes her reunion with Lee Bang-ji. However, Jeong Gi-joon's true purpose was to lure Kang Chae-yun into Milbon through Lee Bang-ji and have her assassinate Lee Do. Meanwhile, Lee Do was attempting to meet Jeong Gi-joon. Muhyul happens to spot Lee Bang-ji in town and asks him to act as an intermediary, believing he knows Jung Ki-joon's whereabouts. ©SBS

Finally revealing himself before Yi Do, Jeong Gijun asserts that he must block the spread of the script to maintain order. Yi Do counters that the script will grant power to the people. As their debate rages on, Kang Che-yun, investigating the hut in Karyong, uncovers the full scope of the secret script. To obstruct the spread of the script, Jeong Gijun assassinated Prince Gwangpyeong. ©SBS

Lee Do regained his composure at Kang Che-yoon's words and began preparations to announce the new script to the world as "Hunminjeongeum." Lee Do entrusted Cho Mal-seon with the investigation into the secret manuscript, and Cho Mal-seon captured the female attendants, including So-i, and expelled them from the palace. ©SBS

Chong Gijun realizes the secret mission to print the explanatory text was entrusted to the female officials. Meanwhile, within the secret group itself, centered around Lee Sin-joo, members begin showing signs of turmoil over the assassination of Prince Gwangpyeong, and Lee Do also senses this internal division within the secret group. ©SBS

Milbon splits into three factions-led by Jeong Gijun, Shim Jongsu, and Lee Sinjoo-to secure Soy's custody. Kang Cheyoon, sensing danger, rushes to Soy's side, only to find she has already been abducted by Yun Pyung. ©SBS

Lee Do attempts to coax Lee Sin-joo into handing over Jeong Gi-jun, while Sim Jeong-su rebels against Jeong Gi-jun, demanding the position of head of the secret society in exchange for surrendering the royal decree. With the day of the character distribution looming the next day, Jeong Gi-jun mobilizes his forces to obstruct the distribution. ©SBS

Realizing the true nature of the Decoding Formula, Jeong Gijun attempts to kill So-yi, but Kang Che-yun appears. Wounded by a poisoned arrow while fleeing, So-yi summons her last strength to complete the Decoding Formula and entrusts it to Kang Che-yun. Meanwhile, the royal palace prepares to hold the distribution ceremony. ©SBS