In the third episode of Moon River, the narrative unfurls with Dal-i being escorted to the traveling merchant's headquarters for her punishment. Her parents, aghast at her predicament, implore Yi Kang for assistance. With unwavering resolve, Yi Kang intercedes on her behalf, rescues her from the situation, and Je-woon, who has brought Kim Ji-pyeong's wife who confesses to framing Dal-i, observes the events unfold. However, Yi Kang rebukes Dal-i for her misadventure, his ire stoked by the fact that she bears a striking resemblance to his wife. Annoyed by his meddling, they engage in a heated argument, culminating in Yi Kang ordering her to leave Hanyang.
Subsequently, Je-woon compels Dal-i to sign a contract stipulating that she will do whatever he demands in exchange for paying for the broken clock. He also implores her to remain in Hanyang. Meanwhile, Yi Kang confides to Shin-won that his harsh words to Dal-i were an attempt to ensure she stays away from him.
En route to meet Woo-hee, Je-woon learns that she is the Left Minister's daughter and destined to marry Yi Kang. He confronts her about this and asks her to elope with him. Instead, she urges him to take his rightful place as Crown Prince through a coup, by his side. Je-woon is unable to agree and apologizes to her. That evening, she summons her palanquin and reveals her gun.
At the palace, Han-chul instructs Yi Kang to fetch his daughter from her temple residence. He then reveals that he has learned of Yi Kang's interference with a female merchant and reminds the prince of his warning—that anyone he comes to love will die.
Je-woon reminisces about meeting Woo-hee as children. After his mother's unjust demise and his subsequent dethronement and exile to Sinjusa temple, where Woo-hee resided, she was the only one who offered him solace. He now writes a farewell letter to her, enclosing the key to the greenhouse where they used to meet inside the envelope. Je-woon then calls Dal-i and informs her that he is allowing her to return home but requests one favor before she leaves.
At the palace, Cha Eun-woo arrives, claiming to be a courier sent to assist with the crown prince's royal wardrobe. Yi Kang and his entourage set out for Sinjusa, and during a rest stop, Yi Kang is surprised to see Dal-i there. Je-woon has asked her to deliver his letter but she is unable to reveal its contents to Yi Kang. They continue their journey together, and Dal-i soon discovers that Yi Kang's betrothed and Je-woon's lover are one and the same.
Following a terse introduction between the prince and Woo-hee, Dal-i presents her with a letter from Je-woon. Woo-hee's expression is clearly one of distress, and she urges Dal-i to leave the temple immediately. Later, when Yi Kang and Woo-hee have the opportunity to speak in private, she reveals that she is aware of the prince's desire for revenge against her father through marriage. She adamantly refuses the proposal, declaring that she will not be a pawn in his scheme.
As this exchange unfolds, a group of men in black ambushes Yi Kang's soldiers, slaughtering them one by one. One of them lunges towards Woo-hee, but Shin-won and Yi Kang intervene, saving her. Yi Kang helps Woo-hee hide while he returns to confront the attackers alongside Shin-won. Together, they manage to set several fires and neutralize all the attackers, but at a cost; Shin-won is gravely injured.
However, it becomes clear that this was all orchestrated by Woo-hee herself. In the end, she emerges with her gun and shoots both men, leaving Yi Kang mortally wounded and plummeting off a cliff into the water below. In the morning, Se-don discovers Shin-won miraculously alive, but they assume that Yi Kang has perished. The news reaches Yi Hui, the king, who is informed that Woo-hee witnessed his fall from the cliff.
Meanwhile, Dal-i is on her way down the mountain when she stumbles upon Yi Kang injured and unconscious near a stream. She gathers medicinal herbs and discovers that guards are searching for him. Assuming he is in danger, she keeps his discovery a secret and treats his wound by extracting the bullet and sealing it with a heated spoon.
Back in Hanyang, Han-chul discusses the situation with his co-conspirators, expressing his desire to prevent Je-woon from taking the throne and plans to eliminate him. Overhearing this, Woo-hee boldly reveals that she has killed the prince and now wants Je-woon to ascend the throne and her to become his queen. Through this, Han-chul would remain the royal father-in-law. She confidently asserts that the cards are now in her hands.
When Yi Kang finally wakes up, he is shocked to learn that Dal-i has been nursing him for fifteen days! With her help, he sends a message to Eun-woo, and together they embark on their long journey back to Hanyang. After two days, Yi Kang's condition worsens, but he refuses to rest and insists on continuing without her. But she does not relent and eventually, in a moment of desperation, Yi Kang asks her to protect him before he loses consciousness again.
