Episode 8 of "Good Partner" kicks off with a tense confrontation between Eun-kyung and Ji-sang, standing on the frontlines of a custody battle, flanked by a seasoned family investigator. The atmosphere is charged as Ji-sang, adhering to his lawyer's strategy, paints Eun-kyung as an absentee parent, while she valiantly defends her career choices, arguing they were solely to secure a prosperous future for their daughter.
Meanwhile, Ji-sang, intent on severing ties with Choi Sa-ra as per his legal counsel's advice, is met with a bombshell revelation: Sa-ra's pregnancy. Parallel to this, Yu-ri, Eun-kyung, and Woo-jin embark on a journey to bring closure to a protracted custody dispute, where the son yearns to reside with his father. However, just as the case seems poised to reach its conclusion, a shocking twist emerges during the hearing—Woo-jin discovers that his client is not the biological father of the child. The mother's deception about the child's paternity has been kept hidden from her husband, leaving him devastated. Driven by a need for certainty, he resolves to conduct a paternity test, stealthily obtaining a DNA sample during a visit from his beloved, yet not biologically related, 18-year-old son.
Elsewhere, Choi Sa-ra remains relentless, her persistence undiminished. She presses Ji-sang to accompany her to the doctor, a request he promptly rejects, making it abundantly clear that securing Jae-hui's custody supersedes all else in his priorities. Undeterred, Sa-ra formulates a plan: to thwart Ji-sang's custody aspirations at all costs.
In a poignant scene, Ji-sang spends quality time with Jae-hui at the amusement park, a cherished haunt from their childhood days. Jae-hui spends the night at Ji-sang's, where she stumbles upon Sa-ra's ultrasound photo, hidden in a drawer, a deliberate ploy by Sa-ra to sow discord. Deeply hurt, Jae-hui seeks solace and guidance from the family investigator, her fragile world shaken to its core.
Elsewhere, Woo-jin's client makes a heartfelt decision to withdraw from the child custody battle, determined to remain his son's legal guardian and loving father, even amidst adversity. Both Woo-jin and Eun-ho, his steadfast supporters in this ordeal, can't help but feel a profound sense of sadness for the unforeseen turn of events their client faces. In a subsequent meeting, Woo-jin witnesses the profound bond between the father and his son, as the young boy expresses his unwavering love and desire to live with his dad.
Meanwhile, Choi Sa-ra confronts Jae-hui with a blunt ultimatum, demanding that she prioritize her mother over her father. Jae-hui, seething with anger at Sa-ra's relentless disregard, retaliates by demanding an apology to her mother.
During the court-mandated mediation, the client triumphantly secures his legal guardianship, granting him unfettered access to his cherished son. As the case concludes, Woo-jin's mind drifts back to his own tumultuous parental past, memories flooding his thoughts.
Later in the day, the family investigator graces Eun-kyung's doorstep, leaving her with an unspoken verdict. However, Eun-kyung intuits that Jae-hui has chosen to reside with her, and she eagerly shares this news with Yu-ri. Seeking clarity, Eun-kyung confronts the investigator, only to be stunned by the revelation that Jae-hui had been aware of Ji-sang's affair for longer than she herself had known.
A poignant flashback reveals Jae-hui's heartbreaking discovery of her father's betrayal while staying at Sa-ra's house, a secret that has haunted her ever since. Jae-hui confides in the investigator, revealing how she had given her father multiple chances to confess, yet he remained silent. She also acknowledges that her mother's lies stemmed from a protective instinct, rather than malice.
The situation escalates into chaos when Eun-kyung stumbles upon Ji-sang's unborn child and realizes Jae-hui is also aware of this bombshell. The emotional weight of this revelation is palpable as Yu-ri, overhearing the conversation outside the room, is left reeling. The episode culminates in a shocking twist, as it is revealed that the esteemed CEO of the law firm, and Woo-jin's uncle, is in fact his biological father, a revelation that sends shockwaves through the narrative.
