Episode 15 of "Buried Hearts" unfolds with a dramatic twist as Jang-seon orders his men to throw Dong-ju off the rooftop. Just at that precarious moment, a drone swoops in, broadcasting Jang-seon's confession about murdering Dong-ju's sister on live news. The confession, captured by a cleverly concealed camera in Dong-ju's wristwatch, sends shockwaves through the air. Jang-seon dismisses the impact it might have on him with a nonchalant attitude. Before departing, Dong-ju confronts Jang-seon, inquiring about the motive behind Il-do's murder. Jang-seon casually responds, blaming Il-do's arrogance and even pointing fingers at Dong-ju, accusing him of indirectly causing Il-do's demise by inciting him to confront Jang-seon.
As the incriminating video spreads like wildfire across social media, the Cha family learns that Dong-ju was behind the hacking of the two trillion won. Meanwhile, Dong-ju rushes to the hospital where he's met with grim news about Won-bae's condition. Despite Won-bae's insistence that he's fine, Dong-ju cannot help but apologize for his part in the ordeal.
Returning home, Jang-seon finds the Elder awaiting him with a stern expression. Jang-seon suggests they could dismiss the video as fake, but the Elder's primary concern lies with the missing money. He orders Jang-seon to retrieve the funds and refrains him from harming Dong-ju until the task is accomplished. Instead, Jang-seon offers the Elder unfettered access to all of Daesan Group's operations.
Elsewhere, Cha Guk-hui aligns himself with assemblywoman Seok Sug-yeong, orchestrating an investigation into the secret slush fund at Daesan Energy. Guk-hui even introduces Sug-yeong to the company's finance manager, facilitating their inquiry.
Informed of this development, Ji Yeong-su relays the information to Jang-seon with urgency. He emphasizes the need to link Dong-ju to the chairman's secret safe containing the slush fund, ensuring Dong-ju's removal from the picture.
Dong-ju visits his sister's grave, memories flooding back as he recalls a tender moment from his youth. In a flashback, a younger Yeong-ju persuades a teenage Dong-ju to focus on his studies while she takes the path of becoming a nun. Now, at his sister's resting place, Dong-ju offers a heartfelt apology and vows to bring an end to his turbulent journey soon. Afterward, Dong-ju makes a bold move by visiting Chairman Cha and delivering a startling proposition: he demands to be appointed as the CEO of Daesan Energy.
At her residence, Ji Yeong-su demands that Deok-hui put her forward for the prestigious position of chairman at the Cha family foundation. Deok-hui, however, declines her request, his refusal tinged with insult. This cordial disagreement swiftly deteriorates into a physical altercation, with Deok-hui grabbing Yeong-su's hair in a fit of rage. Through the transparent glass door of the room, Seon-u stands as an unwitting witness to this domestic drama unfolding.
Elsewhere, Dong-ju elucidates to the chairman the persistent ambition of Jang-seon to seize control of Daesan. Dong-ju recalls a critical juncture when Daesan Energy teetered on the brink of collapse due to Jang-seon's meddling, specifically his obstruction of crucial oil imports. In a flashback, Dong-ju approaches the Elder, revealing his command over the National Patriotic Fund. He bargains, requesting the Elder to facilitate the resumption of oil imports for Daesan Energy in exchange for proof of the fund's existence.
Returning to the present, Dong-ju asserts his unique position as the sole individual capable of thwarting Jang-seon's schemes, urging the chairman to consider his proposition deeply. As Dong-ju prepares to depart, he encounters Eun-nam, whopleads with him to relinquish his ties to Daesan. Dong-ju, however, remains steadfast in his resolve to ensure Jang-seon's departure. In a surprising revelation, Eun-nam admits her awareness of Dong-ju's true parentage.
Meanwhile, Ji Yeong-su seeks out Jang-seon, presenting him with a fragment of the fund records from Chairman Cha's confidential vault. Yeong-su expresses her apprehension about Seon-u's growing infatuation with Dong-ju. Jang-seon suggests she caution Seon-u about Dong-ju's potential bias towards his half-brother, Tae-yun, unaware that Seon-u is already privy to this information.
Dong-ju subsequently encounters Deok-hui, imploring her to bolster his bid for the CEO position at Daesan Energy. He underscores the perilous standing of Tae-yun within the company and asserts that this endorsement is paramount for his position's stability. Shortly thereafter, Dong-ju convenes with the finance manager of Daesan Energy, who divulges that Jang-seon intends to disclose the scandal of the slush fund prior to Assemblyman Seok's press conference. In a bold countermeasure, Dong-ju hosts his own press conference, alleging that unseen forces are obstructing the official probe into the National Patriotic Fund. He also presents fresh evidence implicating Jang-seon in Sister Agnes's demise.
Jang-seon's subsequent strategy involves unveiling to the media Chairman Cha's dementia, accusing Dong-ju of exploiting the chairman's fragile state. Chairman Cha catches wind of this revelation on television, and his anger escalates. Amidst this fury, he begins to suffer from severe stomach aches and is hastily escorted to the hospital. The news triggers a steep decline in Daesan's stock prices. A nostalgic glimpse reveals Yeong-su handing over evidence of Chairman Cha's dementia to Jang-seon. Seizing the moment, Jang-seon devises a plan to acquire more Daesan shares while the market value is at its nadir.
At the hospital, Do-soo imparts to the gathered family that the chairman is suffering from stress-induced gastritis. Shortly thereafter, Dong-ju pays a visit to the chairman and proposes a tender offer as a strategic maneuver to thwart Jang-seon's assault on their shares. Chairman Cha, convinced of its merit, gives his nod of approval.
Dong-ju secures the funds for this tender offer from Madame Pi and Tae-geum, whose father was a prominent figure in the financial realm. However, a distressing turn of events unfolds as Chairman Cha experiences a sudden memory lapse, forgetting who Choi Gi-hyeon is during a crucial meeting attended by both Dong-ju and Gi-hyeon.
Consumed by an urgent impulse, Chairman Cha proceeds to the prosecution service, claiming to possess crucial information regarding Il-do's demise. The subsequent development sees Jang-seon being apprehended on suspicion of murdering Il-do. But just as the arrest warrant is about to be issued, The Elder and Nam Sang-cheol intervene, ensuring that the warrant is Denied. In a bid to soothe his nerves, Jang-seon indulges in some wine with Sang-cheol and is subsequently escorted home in a chauffeured car.
Unbeknownst to Jang-seon, the driver is none other than Dong-ju, who, seizing his moment, halts the vehicle and administers a substance that renders Jang-seon unconscious. As Dong-ju speeds away, the evening news breaks the startling report that Jang-seon has mysteriously gone missing, capping off the dramatic cliffhanger of Buried Hearts Episode 15.
