Episode 9 of "Buried Hearts" kicks off with Yeom Jang-seon immersed in a buoyant mood, eagerly anticipating the demise of both Dong-ju and Eun-nam. Inside the hospital, Tae-yun pays a visit to Dong-ju, who lies unconscious. He drops a bombshell, revealing his awareness that Il-do never dialed 911 on the fateful day Dong-ju collapsed. Il-do, arriving on the scene, eavesdrops on the conversation from just outside the hospital room, his ears tuned to every word.
After Tae-yun departs, Dong-ju miraculously regains consciousness. Meanwhile, Il-do retreats to the bathroom, a syringe poised menacingly at his own neck before he hesitantly lowers it. His inner turmoil unfolds as he contemplates taking full responsibility for his actions once Daesan is safely in Tae-yun's hands. Emerging from the bathroom, he discovers the Administrator assaulting Dong-ju and, without hesitation, intervenes to protect him, knocking the Administrator to the ground.
Elsewhere, the chairman engages in a discussion with Dr. Kang regarding Dong-ju's recovery. As their call concludes, he realizes, to his astonishment, that he has wandered out of his house barefoot, his phone now dead.
Within the hospital's confines, Dong-ju confronts the Administrator in the bathroom, preparing to inject him with the syringe. But just as he's about to administer it, the Administrator spills the beans about Jang-seon's sinister designs on Eun-nam. Dong-ju quickly dials Eun-nam, who is about to share a meal with Jang-seon, unaware of the assassin lurking in the shadows.
Dong-ju and Eun-nam devise a plan to flush out the assassin. Once the danger is neutralized, Dong-ju instructs the Administrator to leave Eun-nam alone. Seizing Il-do's phone, Dong-ju makes a swift exit.
Meanwhile, the chairman wanders aimlessly, struggling to find his way home. Fortunately, Ji Seon-u spots him and recognizes him from his mother's restaurant. Seon-u kindly offers him a ride, even lending him a pair of his new shoes. Back at the Cha residence, concern for the chairman is palpable. Deok-hui's anger boils over when she learns from Guk-hui that she was aware of his dementia but kept it a secret. She lunges at Guk-hui, ready to strike, but Secretary Gong intervenes, shouting for her to calm down.
At the hospital, Il-do liberates the Administrator from his confines. Meanwhile, Jang-seon anxiously awaits word regarding Dong-ju's demise. A nostalgic glimpse into the past reveals Gu-ho presenting Jang-seon with a background investigation on Dong-ju shortly after his employment at Daesan. The revelation unfolds that Dong-ju and Yeon-ju's mother was Ko You-jin, a woman who once graced the stages of Iris, a renowned nightclub, but passed away prematurely. Subsequently, Madame Pi, also a former Iris employee, orchestrated a deal where another waiter surrendered his surname to the orphans, transforming their last name to Seo. Intriguingly, Jang-seon's wife recognizes young Dong-ju as Chu Seong-hyeon, another child she once knew. She spots an antique Daesan Group badge that Seong-hyeon used to wear incessantly, but Jang-seon dismisses her assertions, insisting the two boys are distinct individuals. Little else is unveiled about Seong-hyeon's true identity.
Dong-ju arrives at the restaurant and reconnects with Eun-nam. They make their way to her vehicle, only to find an assailant lurking inside, poised to strike. Dong-ju swiftly disarms the threat and proceeds to call Jang-seon using Il-do's phone, vowing to hold him accountable for all his past deeds. After several circuits around the neighborhood, Seon-u and the chairman finally return home. Despite his confusion, the chairman fails to recognize Deok-hui, mistakenly addressing Seon-u as his son. They venture indoors, where Seon-u kindly asks Deok-hui to provide Dong-ju with cookies from his bakery.
Eun-nam makes an unexpected appearance at Hui-cheol's workplace, informing him that Jang-seon has summoned him. They journey back home, where Hui-cheol encounters Jang-seon, only to be told that no such call was ever made. After Hui-cheol's departure, Dong-ju strolls into the house while engaged in a phone conversation. Jang-seon prepares to pull the trigger when Dong-ju places the call on speakerphone, revealing President Lee Cheol-yeong, alias The Elder, on the other end.
Cheol-yeong urges Jang-seon with a stern warning not to lay a finger on Dong-ju, entrusting him instead with the responsibility of managing the finances from this moment forward. His tone hints at a deep appreciation that Dong-ju hadn't deserted them by absconding with the money, revealing that Cheol-yeong's options are severely limited. Following their conversation, Dong-ju makes his intentions crystal clear: though he intends to seek retribution against Jang-seon, he will do so with deliberate, measured steps.
Il-do finally steps through his front door, greeted by Deok-hui who fills him in on the recent developments. As dawn breaks, Dong-ju pays a visit to the chairman, announcing his decision to expedite Ji Seon-u's incorporation into the family fold. Later, he confronts Il-do, revealing his cunning plan to exploit Il-do's dark secret of attempted murder to his advantage.
Dr. Kang discovers Dong-ju's absence from the hospital and her awareness of this grows. The climax of Buried Hearts Episode 9 unfolds as she assists her father with his phone, her eyes catching an old photograph of him alongside Il-do, Sun-ho, and a youthful figure bearing an uncanny resemblance to Seong-hyeon, sparking a myriad of unanswered questions.
