Episode 8 of "Buried Hearts" kicks off with Yeom Jang-seon giving Gu-ho a dire instruction: to prepare an lethal amount of cinnamon, intended to fatally poison Dong-ju. Separately, Jang-seon meets with Il-do, assigning him the grim task of terminating Dong-ju should he refuse to consume the cinnamon. Soon afterward, Dong-ju collapses, victim to the cinnamon-laced cookies, prompting a frantic rush to the hospital. Hui-cheol hastily informs Dong-ju's aunt of the dire situation, as the prospects for Dong-ju's survival appear grim. Il-do relays this dire prognosis to Jang-seon, who casually reveals his awareness of Dong-ju's true identity—Chu Seong-hyeon.
A fleeting flashback transports us to a moment when Il-do arrives at Jang-seon's abode, Dong-ju in tow. Jang-seon's irritation is palpable at Dong-ju's unwelcome presence, yet Dong-ju hands him a letter from the chairman. The missive reveals that the chairman has declined to dismiss Dong-ju as Jang-seon requested, instead opting to send gifts as a gesture of goodwill. Intriguingly, the chairman also acknowledges Il-do's misappropriation of funds from Daesan for Jang-seon's benefit and chooses to overlook it. The precise timing of this flashback remains somewhat ambiguous.
Returning to the present, Chairman Cha exhibits further signs of dementia, prompting Il-do to seek confirmation from Do-soo about the chairman's declining mental state. Contrary to Il-do's expectations, Dong-ju defies the odds and pulls through. Meanwhile, Madame Pi and Won-bae (alias Il-nam) arrive at the hospital. Won-bae entrusts Eun-nam with Dong-ju's old phone and a small, mysterious package, instructing her to open it in private. Suspecting Jang-seon's hand in Dong-ju's plight, Eun-nam examines the phone and discovers a video of Dong-ju playing the violin on a boat—a poignant memory. Inside the package lies the bracelet that Dong-ju had repaired for her, a poignant reminder of their bond.
A nostalgic flashback unfolds, capturing Dong-ju and Eun-nam engaging in a vigorous run. As Dong-ju catches a glimpse of the scar adorning Eun-nam's wrist, he playfully proposes they ink matching tattoos on their wrists as a gesture of solidarity. They eagerly embark on this shared ritual, and Eun-nam expresses her gratitude to Dong-ju for alleviating her self-consciousness about the scar.
Elsewhere, Guk-hui is summoned to the prosecution's office amidst accusations of lobbying executives at Yuseong Chemical. Chairman Cha, concerned, reaches out to Jang-seon, who swiftly denies any involvement. Following the call, Jang-seon confidentially informs Gu-ho of a shift in strategy – instead of pursuing the two trillion won that preoccupies Dong-ju's mind, he intends to seize control of Daesan.
Meanwhile, Eun-nam seizes her lunch break to meet with Hui-cheol, where she boldly declares her intent to divorce him, even if it means relinquishing the Daesan shares bestowed upon her by her grandfather. Determined to uncover the truth, Eun-nam visits the location of Sister Agnes' demise and secures CCTV footage from a nearby shopkeeper. Upon scrutinizing the tape, she discovers a startling sight – Gu-ho's figure captured in the frame.
Shen meticulously examines another video featuring Dong-ju and notices a boat lurking in the background. Zooming in meticulously, she recognizes Il-do aboard. Just as her revelation sinks in, Il-do strides into the room, warning Eun-nam of severe consequences for violating her prenuptial agreement with Hui-cheol and urging her to reconcile with her in-laws.
Concurrently, Jang-seon orchestrates a meeting with a powerful politician known as The Elder, suggesting they appoint Il-do as the head of Daesan and leverage his position. At Daesan, a seismic shift occurs as Chairman Cha promotes Choi Gi-hyeon to the position of vice-chairman, stunning Il-do. Chairman Cha strategically advises Il-do to confront Jang-seon directly, enhancing his perceived value within the organization. Taking this cue, Il-do confronts Gi-hyeon in his office, revealing Chairman Cha's declining health and commanding Gi-hyeon to consult him on all future matters concerning the group.
Il-do crosses paths with Eun-nam once more, who has returned to Hui-cheol’s abode. She firmly asserts her intention to devise a scheme to secure the funds necessary to nullify the prenuptial agreement. Inside the house, Hui-cheol endeavors to demonstrate his affection towards Eun-nam, yet she remains steadfast in her desire for a divorce. Eun-nam highlights the stark contrast in her treatment post Hui-cheol discovering her affair with Dong-ju, transforming her from a mere companion to a commodity. After Hui-cheol's departure, Eun-nam swiftly dispatches screenshots of Il-do and Gu-ho extracted from videos she discovered to Jang-seon.
Meanwhile, at Daesan, Cha Guk-hui attempts to unlock the concealed safe once more, only to find her possessed code ineffective. Il-do catches her in the act, uncovering her theft of the codes long ago. He consents to conceal her visit, and she departs in a huff. Comparing her slip of paper with his own, Il-do realizes that Dong-ju must have altered the code the day the chairman instructed him to withdraw dollars for Jang-seon. A fleeting memory resurfaces, reminding him of the fateful moment when Jang-seon administered a lethal injection to him.
Jang-seon subsequently reaches out to the administrator, who is still grief-stricken over Yong-chun's loss. Persuasively, Jang-seon诱导 him to undertake a new mission, vowing to support Yong-chun’s family. He then instructs Gu-ho to arrange a dinner gathering involving Eun-nam and Hui-cheol.
Another memory surfaces, depicting Eun-nam's encounter with Jang-seon, where she offered the original photographs in exchange for her divorce from Hui-cheol. In the present, Eun-nam ventures out for the dinner engagement, unaware of a shadowy figure trailing her steps.
At the hospital, Won-bae departs, leaving another nurse in charge of Dong-ju’s care. The administrator arrives to find the nurse slumbering. As he stealthily prepares to inject something into Dong-ju’s IV, Dong-ju awakens abruptly, grappling with the administrator and bringing him to the ground. Dong-ju turns just as Il-do watches from the doorway, a silent observer to this dramatic turn of events, marking the climactic end of Buried Hearts Episode 8.
