Episode Summary
In Lingzhou, Jiang Xu and Shu Jingran investigate Zhang Huaiyu's alleged disappearance, suspecting foul play from Yu Bozhong and Su Erong. Ming Tan investigates a gold shop linked to smugglers and later exposes a merchant's deceit at the Yi Bai Ba Shi Guan, aided by a grateful Wen Zong. At a banquet hosted by Su Erong, Jiang Xu implies Zhang Huaiyu is safe in the capital, unsettling his hosts. Shu Jingran discovers Yun Yi isn't at Su's residence. Jiang Xu tests Yu Bozhong's skills, confirming his suspicions. It's revealed Zhang Huaiyu is actually injured and hiding in Lingzhou. An ambush at the East Temple leads to Yun Yi's rescue and the unmasking of Yu Bozhong as a Haiyou Sect leader. Shu Jingran cares for the injured Yun Yi and wishes for her to leave the Jin Yun Guard. Ming Tan realizes Jiang Xu has been wearing her lost jade pendant since their first meeting.

Spoiler Alert
Youthful Glory Episode 21 Recap & Spoilers: Unmaskings and Hidden Truths
The episode opens in Lingzhou, where Yu Bozhong reports that Zhang Huaiyu, after arriving in the city, frequented the notorious Yi Bai Ba Shi Guan (One Hundred Eighty Hall). He claims Zhang Huaiyu accidentally fell into the water one day and was never seen again. Jiang Xu and Shu Jingran listen intently, their suspicion of Yu Bozhong palpable; their arrival in Lingzhou signals that certain individuals should indeed be wary.
Meanwhile, Ming Tan successfully locates the gold shop previously mentioned by smugglers. However, having already made several purchases that day, she decides against any immediate action to avoid alerting her targets. News of her shopping spree reaches Su Erong; he's informed that a "generous fairy" with an eye for quality has been visiting various shops. While Su Erong doesn't give it much thought, he instructs his men to keep an eye on her.
Jiang Xu confronts Su Erong and Yu Bozhong, demanding they settle their outstanding tax payments. Su Erong, however, diverts the conversation to Ming Tan, reminiscing about their childhood acquaintance and inquiring about her presence in Lingzhou. Jiang Xu curtly informs him that Ming Tan felt unwell and has already returned to the capital.
Later, Su Erong hosts a banquet for Jiang Xu and Shu Jingran, with the local Prefect (Zhifu) and Adjutant (Tongpan) also in attendance. When the conversation inevitably turns to Zhang Huaiyu's case and the need to bring him justice, Jiang Xu delivers a bombshell. He announces his intention to report to the Emperor that very night that Zhang Huaiyu is safe and recuperating in the capital. He pointedly adds that if he hadn't concealed Zhang Huaiyu's whereabouts, Zhang might not have made it back to the capital safely. This declaration visibly unnerves everyone present who was aligned with Su Erong.
Ming Tan, exploring the vibrant city of Lingzhou by night, visits the famed Yi Bai Ba Shi Guan. She observes that business transactions there are swift and direct, a stark contrast to the dealings in the capital. Overhearing a nearby business discussion, she notices something amiss with the quality of silk being presented. Ming Tan steps in, exposing the seller's attempt to pass off inferior goods. A man named Wen Zong, grateful for her intervention, offers to treat her to a meal as a token of his appreciation.
Back at Su Erong's banquet, he attempts to curry favor with Jiang Xu by arranging for Qing Yu, a renowned beauty, to serve him. When Jiang Xu accepts food from Qing Yu without a change in his stoic expression, the tense atmosphere among Su Erong's faction eases slightly. Shu Jingran seizes the opportunity to excuse himself and gather intelligence. A spy reports to him that Yun Yi is not being held at the Su residence.
Ming Tan soon finds herself in a precarious situation, targeted by a certain "Boss Wu." Fortunately, Wen Zong steps in to help her, and her loyal guard, Zhui Yu, arrives promptly to ensure her safety. Wen Zong is clearly captivated by Ming Tan.
Observing that Jiang Xu does not seem to reject Qing Yu's attentions, Yu Bozhong cautiously broaches the subject of the overdue taxes again, hoping for some leniency. Jiang Xu, however, uses this as an opportunity to test Yu Bozhong. He instructs Qing Yu to serve Su Erong wine, a deliberate move to observe Yu Bozhong's reactions and skills. As expected, Yu Bozhong reveals himself to possess uncommon abilities. Su Erong, though puzzled by Jiang Xu's true intentions, becomes more determined than ever that Jiang Xu must not stay in Lingzhou for long. He ominously muses that whatever might befall Jiang Xu on his return journey to the capital would be beyond his control.
A crucial truth is then revealed: Zhang Huaiyu never actually returned to the capital. He is, in fact, injured and in hiding within Lingzhou. The elaborate deception was necessary to mislead the Su family and ensure his safety.
The plot thickens as traces of the Haiyou Sect (Hai You Men) are discovered at the East Temple in the southern part of the city. Jiang Xu and Shu Jingran rush to the location, only to find themselves walking into an ambush. Without hesitation, Shu Jingran charges in to rescue Yun Yi, who is found in a very weakened state. Faced with numerous Haiyou Sect members, Jiang Xu instructs Zhui Ying and Shu Jingran to evacuate Yun Yi while he confronts the attackers. The leader of the Haiyou Sect offers to cooperate with Jiang Xu. In a stunning turn of events, Jiang Xu rips off the leader's mask, exposing him as none other than Yu Bozhong.
In the aftermath, Shu Jingran entrusts the severely injured Yun Yi to Ming Tan's care. Yun Yi, biting back her pain, silently endures, her mind replaying the moment Shu Jingran shielded her from a blow.
Upon learning that Ming Tan encountered Wen Zong earlier that day, Jiang Xu instructs Zhui Yu to investigate Wen Zong thoroughly. Shu Jingran, deeply concerned for Yun Yi, expresses his wish for her to leave the Jin Yun Guard and asks Jiang Xu to release her into his care. Jiang Xu clarifies that Yun Yi is now considered part of Ming Tan's retinue, and therefore, the decision is no longer his to make. Ming Tan advises Shu Jingran to carefully consider his own circumstances, especially his parents, before pursuing this further. She also emphasizes that ultimately, Yun Yi herself must consent.
Later, Jiang Xu pulls Ming Tan aside, a subtle irritation visible in his demeanor. However, Ming Tan focuses the conversation entirely on the ongoing smuggling investigation, making no mention of Wen Zong. As Yun Yi rests fitfully due to her injuries, Shu Jingran remains faithfully by her side, watching over her.
The episode culminates in a poignant discovery for Ming Tan. She realizes that the Wu Heng jade pendant which saved Jiang Xu from a sword strike was originally hers. She had lost it during their first encounter at Hanshan Temple. Jiang Xu had found the jade, kept it, and has been wearing it every day since.