The powerful politician Kim Ja-jeom (actor Park Geun-hyung) leads a political party that engages in rampant corruption. Bulgasari, a gang member and human giant, appears in Hanyang and terrorizes the people.
One day, a lone young man wearing a blue hat faces Bulgasari, who was assaulting people. The man’s name is Iljimae and Bae Sun-dal (actor Kang Nam-gil) and Cha-dol (actor Lee Hyun-woo) trace his exploits to write a series of books called “The Story of Iljimae (紀異 一枝梅傳).”
Always leaving behind an apricot tree branch in places where he strikes, Iljimae was raised by Geol-chi (actor Lee Gye-in) and Monk Yeolgong (actor Oh Young-soo) and then adopted by a rich Chinese family in the then Qing Empire. Loved dearly by his foster parents, Iljimae learns things about his past from the Qing imperial spy Wang Hengbo (actor Park Cheol-min). Wang also tells him who his parents are and this weighs on Iljimae’s mind.
“Apricot tree blossoms emerge from snow-covered trees. As your mother, I cry that I must part with you.” That was the short message his mother left for Iljimae. Iljimae decides to leave his beloved foster parents and return to Joseon with Wang Hengbo...
Iljimae leaves his foster parents and heads to Joseon with Wang Hengbo and arrives in his country after fending off an attack from people pursuing them. He goes to nobleman Kim Cham-pan’s home to meet his father but upon seeing that there is a funeral for his grandmother, he turns back.
Meanwhile, Wang Hengbo engages in spying activities and gets promptly arrested by Koo Ja-myung who acted quickly to apprehend him. Wang Hengbo is then jailed. Iljimae is arrested too because he is posing as a person from the Qing Empire. He meets Koo Ja-myung for the second time in his life. Koo Ja-myung instantly recognizes Iljimae as the son of Baek-mae and takes him to meet his father...
When Iljimae’s father tells him sternly that he is not his father, Iljimae endures the worst betrayal in his life. Iljimae escapes from prison and lives in a cave. He steals chickens from the village for food. Wang Hengbo who escaped from prison together with Iljimae returns to the Qing Empire. Koo Ja-myung pursues Wang Hengbo in a long chase that takes him 600 kilometers across the kingdom. Meanwhile, Iljimae meets a girl called Dal who lives in the mountain with her father. He comes to live with them and learns the Jangbaek sword fighting style from her father Kang Sae-wook.
After setting off in pursuit of Iljimae, Koo Ja-myung stops by one local town to track down a chicken robber. His investigation takes him to a hut where Dal lives. Koo Ja-myung ensnares Iljimae by having a Damo servant disguise herself as Dal. Meanwhile, Koo Ja-myung learns the true identities of Dal and Kang Sae-wook and has them executed according to the law since they are fugitives.
After witnessing Dal’s execution right before his eyes, Iljimae is shocked by the death of someone he loved and goes on a rampage in Hanyang like a wild wolf...
Monk Yeolgong keeps Iljimae locked away for 10 months after restraining him. Iljimae then reappears in the kingdom. Through Monk Yeolgong’s teachings, Iljimae becomes enlightened and finds his true calling as a hero who is at peace with himself and no longer harbors any anger towards people.
After parting ways with Monk Yeolgong, Iljimae seeks out Geol-chi who raised him when he was a baby and settles down in a peaceful life on an island village for a while. But a terrible incident occurs among the single maidens of the village as they jealously try to win Iljimae’s affection…
Iljimae becomes shipwrecked in Wa (Japan) after facing high waves at sea. A group of people from a village of ninjas save his life. A family whose members are ninjas take in Iljimae and nurse him back to health. Rie, the daughter of the ninja family patriarch, has an unknown disease which Iljimae cures by giving her Joseon (Korean) ginseng. The family repays Iljimae by teaching him their ninja skills.
Meanwhile, Koo Ja-myung is sent into exile as punishment for failing to catch Iljimae and solving the murder cases that were believed to have been committed by Iljimae. While in exile, he saves Baek-mae’s life. But Baek-mae treats him coldly once again and they part ways. Around that time, the Bongsun gang and Haedong gang engage in a turf war in Hanyang since Iljimae can no longer stop them. The gangs harm innocent people who are caught in the middle of the gang war. But Iljimae returns to Hanyang after a 3-year absence.
As the gang war between the Bongsun gang and Haedong gang intensifies with more bloodletting, Koo Ja-myung is called back to the city of Hanyang to stabilize the situation. Fearing the return of Koo Ja-myung, Wang Hengbo escapes from prison by using a martial arts technique that he perfected during his incarceration. He then joins the Bongsun gang.
Returning to Hanyang after residing in Wa (Japan) for three years, Iljimae seeks out Wol-hee who had been anxiously waiting for his return. They rekindle the love they had for each other. Iljimae learns of a dark plot hatched by a band of robbers by disguising himself as a gisaeng. Iljimae gives Wol-hee an item that he asks her to hide so that no one can find it but...
Upon stealing gold bars from Kim Ja-jeom and the Bongsun Gang, Iljimae smelts the gold to make a golden apricot tree branch and starts to attack bandits with vengeance. Wang Hengbo, now a member of the Bongsun gang, faces Iljimae in a duel. Wang Hengbo is overwhelmed by Iljimae’s greatly improved martial arts skills and runs for his life.
Meanwhile, Koo Ja-myung infiltrates the Haedong Gang as an undercover agent to try and destroy both the Haedong and Bongsun gangs that terrorize Hanyang. Koo Ja-myung succeeds in bringing down the Haedong Gang but...
While at the market with Wol-hee, Iljimae spots Geol-chi by coincidence and asks Wol-hee to find a way to secretly provide a home for him. With Iljimae’s help, Koo Ja-myung is able to arrest the last remaining Bongsun gang member in Hanyang.
Meanwhile, Iljimae teaches Nobleman Yoon a lesson after he arbitrarily stole land from poor farmers by using force. While Iljimae continues to fight crime, Koo Ja-myung, who suffered a serious injury from a Bongsun gang member, goes to Songdo island where Baek-mae lives by herself to tell her news about her son Iljimae.
After arriving in Songdo Island, Koo Ja-myung tells Baek-mae about news of her son and also confesses his love to her.
Meanwhile, Iljimae continues his crusade to protect the weak from the corrupt noble class and steals food and money from one nobleman who has tons of grains in his storage room and then distributes it to poor, hungry commoners. This makes him an enemy that must be eliminated at all costs among the noble class and a hero among the commoners. But when Iljimae is put in a situation where he has to do the decent thing and marry Wol-hee after cohabiting with her, he worries about his circumstances and the fact that he still hasn’t forgotten his late sweetheart Dal...
After vowing to marry Wol-hee, Iljimae dwells on his memories of Dal and this makes him have second thoughts. Iljimae hardly gets a day off as he is busy countering the corrupt government officials. One day, he rescues a young noble lady from danger and leaves her in the care of Wol-hee. The relationship between the noble lady and Wol-hee deteriorates when she starts to show a romantic interest in Iljimae.
Meanwhile, Cha-dol, who has become a popular storyteller at the market, is kidnapped by a nobleman who was attacked by Iljimae for running a money-lending business with crushing interest rates.
Iljimae rescues a young girl from Son Seok-joo who was a friend of the young girl’s father and wanted her as his concubine. After this, Iljimae thinks about how poor Dal was executed even though she was innocent.
Meanwhile, Baek-mae heads to Hanyang to commit the rest of her life to Koo Ja-myung who told her that he’d help her be reunited with her son. But Koo Ja-myung becomes worried when he continues to hear about the exploits of Iljimae. Since Iljimae has mixed feelings about the direction of his life, he acts distant towards Wol-hee and this breaks her heart. Not wanting to ever see his loved ones die at the hands of his enemies again, Iljimae decides to assassinate Son Seok-joo and send a strong message to the noble class...
Wol-hee is arrested by the royal police when Yang-po tipped off the police about the whereabouts of people who are close to Iljimae. In the meantime, Baek-mae, who is Iljimae’s mother, arrives in Hanyang to meet Koo Ja-myung. After Koo Ja-myung promises that he’ll risk his life to ensure that Iljimae will not be caught by the authorities, she prepares a nice dinner for him and then leaves his life again.
Meanwhile, Cha-dol helps Iljimae and Geol-chi escape to the cave where Iljimae used to use as his hideout. Yang-po tips Iljimae off that Wol-hee is being transferred to the Royal Interrogation Office and so Iljimae risks his life to rescue her.
Iljimae seeks out Koo Ja-myung even though it puts him at danger because his mother is with him. But Iljimae is unable to meet her mother as their paths cross. Around that time, a person posing as Iljimae attacks the royal police station and so a gang of thieves who were imprisoned there are able to escape during the confusion.
Iljimae hunts down the people who posed as Iljimae and do bad things. This takes him far away to Gyeongsang Province. Wol-hee falls into despair when Iljimae leaves her once again. Koo Ja-myung also sets off to find Baek-mae who left him and is determined to win her heart.
Iljimae heads to Jeolla Province to hunt down Wang Hengbo and his gang who are posing as Iljimae while doing evil things. But along the way he is attacked by assassins hired by Kim Ja-jeom who wants Iljimae dead. Iljimae successfully fends them off. Iljimae also foils Wang Hengbo’s latest plan to free a gang of thieves in jail so that he can enlist them in his gang and build a bigger force. But Wang Hengbo crafts another sinister scheme.
Meanwhile, Wol-hee goes to Jeolla Province with Geol-chi to find Iljimae and after a tough journey, she is finally reunited with Iljimae who he treats her coldly and thus, breaks her heart again…
Wol-hee jumps off a cliff after having her heart broken by Iljimae, who then believes she died from the fall. At a bar, Iljimae sees Jang-ho who was being a rowdy customer. Iljimae learns that his father is spying for the Qing Empire and ordering the assassination of people who oppose the Qing. Iljimae kills Jang-ho and his father, making him the most wanted man in the kingdom. This makes it harder for Iljimae to find a safe place to hide. Kim Ja-jeom deploys a team consisting of a seer and gunslinger to kill Iljimae who suffers a bullet wound from them.
Meanwhile, Wol-hee is rescued by Geol-chi after she jumped off the cliff and then makes her way back to Hanyang...
After sustaining a deadly gunshot wound, Iljimae barely reaches Monk Yeolgong’s temple in the nick of time. Meanwhile, Wol-hee meets Monk Yeolgong by coincidence while she was waiting for Geol-chi who unbeknownst to her had already been captured by the police. With the monk’s help, Wol-hee is able to safely arrive at his temple. Wol-hee faithfully tends to Iljimae’s wound as Iljimae is on the brink of death and miraculously survives. When Iljimae opens his eyes, he is surprised to see that Wol-hee is alive and they have a happy and teary reunion.
But Monk Dokbo tips Kim Ja-jeom off on the whereabouts of Iljimae and Iljimae finds himself on the run again…
Kim Ja-jeom uses Wol-hee to bait Iljimae but his plan backfires when Iljimae succeeds in rescuing Wol-hee and also stealing Kim’s stash of money. The gunslinger Park Soo-dong and his team are sent again by Kim Ja-jeom to hunt down Iljimae but they decide to call off the hunt after meeting Iljimae who uses his power of persuasion to make them halt the hunt. This angers Kim Ja-jeom.
Upon the advice of Bae Sun-dal, Iljimae helps minister Choi Myung-kil who has been commissioned by the king to develop gunpowder. Iljimae provides him with the funds and land to work on his gunpowder research. Meanwhile, Yang-po, who had mysteriously helped Iljimae at times while putting him in danger as well, meets with Wang Hengbo and reveals his secret to him as a fellow Qing citizen and suggests that they join forces…
Iljimae works at the Dohwiso Weapons Center with minister Choi Myung-kil, who was given a royal order to develop gunpowder. Iljimae takes it upon himself to guard the center from spies. When Iljimae doesn’t show up all day, Wol-hee, who cooks for the weapons center people, starts to pout. Iljimae warns Kim Ja-jeom to stay away since he is wary of the Dohwiso Weapons Center. Then Kim Ja-jeom and Iljimae face each other on a road inexplicably...
Eventually, Kim Ja-jeom learns that the Dohwiso is developing gunpowder and so he sends a gang of men to attack the center and sabotage the project. A big explosion occurs at the Dohwiso during the attack. Meanwhile, Yang-po and Wang Hengbo surround the center as they intend to seize Iljimae and take him to the Qing Empire.