As the rain pours down, Sun-woo kneels in front of the torn banner, fixated on the drawing of the dragon-head charm under the word "king." The full truth hits him: his friend Mak Mun was killed because he saw the king, and the dragon-head bracelet (that Sun-woo picked up after his fight with the man be believed to be Mak Mun's killer), is the symbol of the king.
Ah Ro finds Ji-dwi in the storeroom and assures him that nobody will believe the banner saying that the king is in Hwarang. Ji-dwi admits he's not as worried as he thought he would be if this happened. He wonders if it's because he has Ah Ro on his side, and she promises that she won't tell anyone he's the king.
Ji-dwi says that if anyone finds out, one of two things will happen — either he'll be killed by assassins, or he'll become king. He confesses that he's more worried that people will ask him to become king.
The other Hwarang are all abuzz wondering who the king could be, and Han-sung guesses that it's either Ji-dwi or Sun-woo. He argues that they're the only two they didn't all know growing up, and he grins when Yeo-wool says he might be onto something.
Hwa-gong recalls his conversation with Queen Regent Jiso, when she'd asked him to prove Ji-dwi's identity. He links it to his talk with Ji-dwi about the hidden king, and how Ji-dwi said he wants to take down the queen regent. He chuckles to himself as he puts the pieces together.
Yeo-wool's theory is that Sun-woo is the king, since he's seen the dragon-head bracelet Sun-woo wears, and he saw the same symbol on the banner. He teases Ban-ryu that he must feel better knowing he got beat up by the king and not a low-born, ha. His theory sweeps through the Hwarang, and when Sun-woo shows up for class, all the boys are super awkward.
Ji-dwi sits next to him and notes that everyone seems interested in Sun-woo. Sun-woo just says darkly that he's interested in them, too, thinking that the person responsible for Mak Mun's death is here.
Han-sung visits Ah Ro to tell her that her "brother" is the king, but she firmly counters it's not true. He asks how she's so sure, and smirks when she can't explain how she knows. She nearly bites the poor kid's head off.
She goes looking for Sun-woo, and catches up to him just as Princess Sookmyung approaches him. Sookmyung tells Sun-woo that people are saying he's her brother, and she takes his wrist to look for a birthmark. Sun-woo's face hardens, and he yanks her closer to him.
He asks if she shot at Ah Ro, and Sookmyung says she was just hunting deer. Sun-woo growls that he's not interested in who she is, or who she thinks he is, but he tells her that if she ever hurts Ah Ro, she'll find out who he really is. Sun-woo stalks off, and Sookmyung looks over to see that Ah Ro witnessed their confrontation.
Queen Regent Jiso is desperate to know who placed that banner in Hwarang, but the only clue is that whoever it is, they know that the double dragon heads are the symbol of the king. It's a closely guarded secret, known only to the royal family and a few generals stationed on the borders. But Hyun Chu thinks this could turn out to be beneficial to the king.
The court officials gather to discuss the increased attacks from the Baekje kingdom. Minister Park blames the situation on the queen regent's divided attention as she focuses on the king in the Hwarang.
His statement is calculated to shock the officials, and it works beautifully. When pressed for an answer, the queen regent lies that the king is not in the kingdom, and calls the rumor false.
In private, Ho Gong guesses that Sun-woo is the hidden king, based on the fact that he's the queen's Hwarang. But Minister Park looks skeptical, thinking it's all too perfect, and he says they'll wait to see what happens next.
Sun-woo goes to his dorm room that evening to find all of his roommates looking at him suspiciously. Yeo-wool points out the elephant in the room and says it's nice to have the king as a roommate, and Ban-ryu just asks Sun-woo straight out if he's the king. Sun-woo rolls his eyes and goes to bed, refusing to answer (and thus infuriating) Ban-ryu.
The Hwarang cringe away as Sun-woo and Ji-dwi walk together across the courtyard, and Ji-dwi says he thinks they're all staring at Sun-woo. Sun-woo asks if he's that good-looking that even men are attracted to him, and Ji-dwi comments on his sudden-onset sense of humor.
Sun-woo asks who Ji-dwi thinks is the king in Hwarang, but Ji-dwi grows too nervous to answer. Ji-dwi asks why he wants to know, and what he'll do if he finds out. Sun-woo answers, "I'm going to kill him."
Sun-woo goes to Ah Ro to re-bandage his wound, and he tells her that the rumor isn't true. She says she knows, and Sun-woo teases her, asking if she can't see him as a king. He's disappointed when she doesn't laugh, but when she stands to move away, he pulls her back to wrap his arms around her waist and lay his head against her stomach.
The Hwarang get another day off, and Ban-ryu goes home and tells Minister Park about the banner. Minister Park pretends to be surprised to hear that the king is in Hwarang, but Ban-ryu isn't fooled, and he asks Minister Park if this wasn't his doing.
Minister Park just presses for information on Sun-woo, and he tells Ban-ryu to find out if Sun-woo is the king. Ban-ryu asks why he has to do things like this, and Minister Park finally tells him that he's thinking of making Ban-ryu the king.
Soo-yeon lurks outside the house, hoping to see Ban-ryu. She gets excited when he finally comes out, but he walks right past her, and she has to run and catch him. She gives him her brightest smile and says he must not have seen her, but he just nods distractedly and walks past her again.
Su-ho comes upon his sister just as she's bursting into tears, and he sees Ban-ryu walking away and assumes the worst. He's ready to go beat Ban-ryu to a pulp, but Soo-yeon wraps her arms around him and stops him, still sobbing.
Han-sung goes to see Ah Ro in the infirmary, whining like a big ol' baby as she checks out his sore ankle. He gets distracted and forgets to complain for a moment, and Ah Ro realizes he's faking. She pulls out her biggest acupuncture needles and advances on him, and he admits he's fine.
Ah Ro asks why, and Han-sung says he doesn't like being compared to his older half-brother Dan-se during training. He says it would have been better if Dan-se had been born in his place (as a full-blooded True Bone).
Dan-se walks in and tells Han-sung to follow him. Han-sung refuses for a moment, until Dan-se offers to help him with his swordsmanship, and he reluctantly goes.
Dan-se doesn't go easy on him, and he roughly knocks Han-sung's practice sword from his hands. Han-sung starts to look angry, and when Dan-se knocks him to the ground, he explodes. He refuses to practice any more, and says that their births should have been switched.
He thinks Dan-se should have been the heir, so that he could have rebuilt their family to its former glory. Han-sung says that he just wants to look at the stars, that he's terrible at swordsmanship and archery, calling himself a disappointment to the family. He yells, "But what should I do? This is just who I am!"
Sun-woo visits Ji-gong, who checks his arrow wound and pronounces him fine. He shows Ji-gong the torn banner with the dragon-head drawing, and tells him that just before he was killed, Mak Mun said he saw the king.
He continues that the man who wielded the sword was wearing this symbol, unaware that he's muddling events in his mind (Ji-dwi didn't come by until after Hyun Chu killed Mak Mun and injured Sun-woo). Sun-woo thinks that the symbol means that the king killed Mak Mun. Ji-gong asks what Sun-woo plans to do, and Sun-woo says that he has to kill the king.
Ah Ro stays up late pacing her room, wondering what to do. She can't tell anyone that Ji-dwi is the king, but it's the only way to prove that Sun-woo isn't the king.
Hyun Chu reports to Queen Regent Jiso that there's a misunderstanding in Hwarang that Sun-woo is the hidden king. He thinks this is a good thing, as it deflects attention from the real king. But he anticipates Ji-gong being a problem, so the queen regent decides they'll have to make him stay away.
She goes to see Ji-gong personally, claiming she needs a checkup from her doctor. She offers to spare Ah Ro's life in return for a favor from Sun-woo — but if Sun-woo doesn't fulfill her wish, Ah Ro dies.
Ji-gong is still shaking after she leaves, and Hwi-kyung comes out from where he was listening in the next room. Ji-gong asks what he should do to the woman who killed his wife and son and threatened his daughter, but he answers his own question — he must kill her and her son.
Later that night, Hwa-gong runs across Ji-dwi roaming the Hwarang grounds and asks why he's spending his day off here. Ji-dwi says he has nowhere to go, and Hwa-gong asks about his name. Ji-dwi says it stands for "unmercifully stab (someone) in the back," and Hwa-gong chuckles.
He mutters that Ji-dwi doesn't know anyone in the capital, his name is an alias, and his family is a mess. He adds that Ji-dwi's sister is here in the Hwarang grounds and his mother is in the palace, and Ji-dwi realizes that Hwa-gong knows the truth.
Hwa-gong faces Ji-dwi and says in a whisper, "Isn't that so, Your Majesty?" He gets on his knees to bow to his king.
In the morning, the queen regent asks Su-ho's father if she can meet his son, saying that she's heard about his excellent swordsmanship. Su-ho is thrilled by the summons, though his father is nervous to send him to the palace alone.
The queen regent is taking a barefooted stroll in the grass when Su-ho arrives, and he rushes to her when he sees that she's about to tread on a thorny branch. He offers to carry her but she haughtily refuses before immediately stepping on a thorn. Su-ho sweeps her up in his arms and carries her to her quarters, looking nervous but determined.
The queen regent lets Su-ho remove the thorn from her foot as he explains that he encounters these thorn plants often while hunting. He apologizes for daring to touch her, but she just asks if he knows Sun-woo.
Sun-woo glares at his fellow Hwarang, wondering which one is the king that killed his friend. When Ji-dwi comes into view, Sun-woo stares at him with particular suspicion.
Ah Ro finds Princess Sookmyung in her infirmary, and the princess tells her to come to her room to look at her twisted ankle. Ah Ro snarls behind her back but shows up anyway, and the princess commands her to wash her feet.
Ah Ro says that's a job for her maid, but the princess reminds her that she's her personal doctor now. Angry, Ah Ro snaps that Sookmyung shot at that personal doctor and injured her brother. Sookmyung doesn't deny it, saying that she heard the queen regent wants her dead.
She tells Ah Ro that since she didn't die, it's her duty to wash and heal her feet, nastily calling her a half-blood. Ah Ro really loses her temper, and tells the princess that for her brother's sake, no matter how high her status is, she can't go around killing people.
She turns to leave, but Sookmyung stops her and asks if she really knows her brother. She says it's unfair that Ah Ro knows who he is when she doesn't, and orders her to reveal his identity. Ah Ro says that she doesn't know, but she wouldn't tell Sookmyung even if she did.
Kang Sung shows up at the stables to heckle Dan-se, sneering that even though they're both Nando, they're still not on the same level. Dan-se doesn't respond — instead, he calls Pa Oh over to meet Kang Sung, and points out that he's two years younger than they are.
Kang Sung taunts Pa Oh about his age, and Pa Oh shoots him some epic stink-eye. He grabs Kang Sung by the collar and pulls him halfway over the fence, instructs him to call him "hyung," then dumps him in the straw.
He leaves, and Dan-se crouches to tell Kang Sung that he saw him destroy the instruments at the Moon Festival. He says calmly that he doesn't care why Kang Sung is here, so long as he leaves him alone.
Sun-woo seems particularly worked up while he and Ji-dwi practice their swordsmanship, and he thinks about the voice of the man he fought saying that there are doors that people like him shouldn't open. He goes after Ji-dwi with surprising fury, and it's clear that Ji-dwi senses something wrong.
After practice, Ji-dwi asks Sun-woo where he learned to sword fight. Sun-woo gives him a dark look, but then he remembers Ji-dwi saying that he's the only friend he's ever had. He relaxes when Ji-dwi makes a dog poop joke, and chases after Ji-dwi as he taunts him, whatever was bothering him forgotten for now.
Dan-se hears that Han-sung has gone missing, and that he's staying in Ban-ryu, Su-ho, and Yeo-wool's room now after getting chased from his own. Dan-se runs off to their room, and finds Han-sung huddled in a closet.
He asks if Han-sung is just going to avoid sparring because he doesn't like it, but Han-sung says sparring isn't the issue. He yells that he doesn't want to participate in this dangerous fight the Hwarang are participating in, and he gets even more upset when Dan-se reminds him that he's the family heir.
Han-sung says that he didn't choose to be born the heir, frustrated that everyone is putting so much pressure on him. Dan-se gets angry in return, asking Han-sung why he wasn't born the half-bone then. With tears welling in his eyes, he tells his brother that if he has everything, then he should at least try to prove he deserves it.
Ji-dwi broods over Sun-woo's statement that he wants to find the king and kill him. Meanwhile, Sun-woo thinks about how interested Ji-dwi was in the dragon-head bracelet and seems to come to a realization.
The Hwarang line up in front of the palace, prepared for the fight that Princess Sookmyung has ordered. The queen regent and the royal council are all in attendance, and Hwa-gong quietly pleads with the queen regent not to let the Hwarang draw each other's blood.
The queen regent ignores him as she stares down at Ji-dwi, silently asking him to beg for his life. He looks back up at her, and thinks that he won't avoid this challenge — he'll face it and win, and take his rightful throne.
The sparring starts with a match between Ban-ryu and Su-ho, and Su-ho's superior fighting skill is quickly apparent. He slashes Ban-ryu's side, then hesitates at the sight of the blood on his sword. Ban-ryu nods at him and they engage again, but their fight isn't nearly bloody enough for the princess, who complains to Hwa-gong.
Hwa-gong says that they know there are more important things than killing. The princess gestures for the fight to be stopped, prompting Minister Park to comment that the Hwarang hasn't got much to show them.
He suggests that his highly-skilled bodyguard spar with one of the Hwarang, and the princess agrees. Minister Park asks to choose the Hwarang, and he picks Sun-woo, of course.
Su-ho tries to take his place, but Sun-woo refuses his offer. He climbs the stairs to pay his respects, and Minister Park says that even if one of them is killed, the winner won't be held responsible.
Everyone looks nervous, aware that Sun-woo's sword fighting skills are still rough at best. The queen regent snaps at Minister Park that it's disloyal to make the king's Hwarang endure this, but he says this will only make them stronger.
The fight begins, and in only three moves, the bodyguard manages to slash Sun-woo's thigh. Minister Park chuckles that he was worried Sun-woo was the king, but this lays his suspicions to rest. Sun-woo defends himself for a few more seconds, then takes a second wound to the shoulder.
He falls to the ground, and Minister Park calls to his bodyguard that this is a fight to the death. The bodyguard raises his sword to strike a killing blow, but at the last second, the queen regent yells for him to stop.
The bodyguard turns to walk away, but Sun-woo stands and makes a flying Dog-bird leap to land in front of him. They continue the fight, and Sun-woo makes another leap, this time slashing the bodyguard's topknot right off his head as he passes him.
The fight is over, and the Hwarang all celebrate loudly. The queen regent looks relieved, and even Hwa-gong lets loose a wild grin before composing himself. Minister Park thinks to himself that now he has his answer.
Ji-dwi finds Sun-woo alone after the fight, and asks if he's okay. Sun-woo asks if he cares, and scoffs when Ji-dwi says that he does. He levels his sword at Ji-dwi's neck and asks quietly, "Is it you? Are you… the king?"