Episode 6 of "Buried Hearts" kicks off with Dong-ju enduring harrowing torture orchestrated by Jang-seon's henchmen. Meanwhile, at the hospital, a palpable sense of anxiety grips Il-do, Eun-nam, and the rest as they brainstorm ways to locate Dong-ju. Do-su cautions against informing the chairman, fearing the grave impact such news might have on his frail health. Through his contact, Jang-seon receives a startling revelation—Dong-ju's memory loss might not be a ruse.
After escorting Sister Agnes back to her church, Eun-nam learns from her an intriguing tidbit: Dong-ju's childhood name was Seong-hyeon, a detail he had forgotten as he matured. Back at the hospital, the chairman's realization that Dong-ju is missing strikes like a bolt of lightning.
Dong-ju's ordeal intensifies until an eerie silence envelops him, rendering him unresponsive. His captors, misunderstanding his stillness as compliance, untie his hands. Seizing this fleeting moment, Dong-ju retaliates with a burst of strength, incapacitating them both. The guard stationed outside, who doubles as Jang-seon's informant, attempts to knock Dong-ju unconscious once more, but Il-do intervenes, saving him at the eleventh hour.
Dong-ju urgently pleads to be taken to the chairman, and Il-do complies, albeit with Jang-seon already present. In a brazen display, Jang-seon claims responsibility for Dong-ju's rescue, fabricating a shadowy figure as the culprit. When the chairman suggests involving the police, Il-do swiftly diverts attention by revealing a gunshot wound on Dong-ju's body—unaware that Dong-ju retains the memory of Il-do being his assailant. Dong-ju, too, voices his opposition to law enforcement involvement. The chairman, resolute, insists that Dong-ju stay under his protection.
Elsewhere, Jang-seon and Il-do confer privately. Il-do lays out the grim scenario: if the chairman discovers that the account password resides solely in Dong-ju's mind, Jang-seon's fortune could vaporize. Leveraging this point, Il-do negotiates a slice of the two trillion won pie from Jang-seon. Reluctantly, Jang-seon agrees to part with 10%, contingent on Il-do first securing the password.
Meanwhile, Jae-pil, the Cha household's seasoned chef, delivered Dong-ju's meal with meticulous care. Closely trailing him was Secretary Gong, who brought along the very raw egg drink that Dong-ju and Chairman Cha once shared with great relish. Dong-ju casually inquired if the name Seong-hyeon had startled her, to which she feigned indifference, responding with a lie that it hadn't. When Dong-ju brought up his dream about the car accident, Secretary Gong's anxiety became even more palpable.
Later that evening, Dong-ju awoke with a jolt, unable to shake off the disturbance. Tossing and turning in bed, he resorted to the pull-up bar, a piece of equipment usually monopolized by Il-do. Surprisingly, Il-do was also awake and stumbled upon Dong-ju's impromptu workout. Eventually, Il-do ushered him away, but Dong-ju abruptly asked if Il-do had been the one to shoot him. Il-do dismissed it as a case of mixed-up thoughts, which Dong-ju seemed to accept before retreating to his room. Il-do, armed with a hefty dumbbell, intended to follow but was waylaid by Deok-hui, who was on her way to deliver Il-do's morning herbal tonic.
Il-do then phoned Dong-ju, proposing a solution to restore his lost memories. He escorted Dong-ju to the abode of Dr. Kang I-hyeon, whose father was a close friend of Il-do's. I-hyeon graciously agreed to lend a helping hand in unraveling Dong-ju's forgotten past. Later, as Il-do chauffeured his friend (I-hyeon's father) somewhere, he nostalgically reminisced about the bygone days when they, Il-do, Deok-hui, and Sun-ho (Eun-nam's father) shared countless joys together.
During his session with Dr. I-hyeon, Dong-ju's mind wandered back to a time when he was being driven in a car. Vividly, he recalled a man at the wheel and a little girl seated at the back. Elsewhere, Jang-seon engaged in deceitful conversation with a politician, pretending to still wield influence over the national patriotic fund. When Il-do called to update him about the hypnotherapy, Jang-seon seized the opportunity to inform Eun-nam of his desire to speak with her.
Suddenly, Dong-ju awoke from his hypnotic trance, screaming in terror. Once he had calmed down, I-hyeon gently inquired if he wished to reunite with his sister. Eun-nam picked him up, and during the journey, Dong-ju couldn't help but notice their matching tattoos. They arrived at a prearranged meeting spot just as Sister Agnes stepped onto the road, only to be violently struck by a speeding truck. The impact was devastating, and in that heart-stopping moment, Dong-ju's memories flooded back with overwhelming force.
Through Jang-seon's internal dialogue, it was revealed that he had orchestrated the attack with the sole purpose of jolting Dong-ju's mind and restoring his lost recollections.
