The central pillar of the series' plot is the mystery of Woo Young-woo's parentage. It is revealed midway through the series that her mother is Tae Soo-mi (played by Jin Kyung), a star attorney and CEO of the rival Taesan Law Firm and the nominee for Minister of Justice. Tae Soo-mi abandoned Young-woo as a baby due to fears that having a child out of wedlock with a man of lower status would ruin her career. This revelation re-contextualizes the entire story: Woo Gwang-ho didn't just raise his daughter alone; he gave up his own promising future to do so after being forced into silence by Soo-mi's powerful father. Furthermore, Han Seon-young, the CEO of Hanbada, hired Young-woo intentionally as a strategic move against Tae Soo-mi, her university rival, adding a layer of political maneuvering to Young-woo's journey.
The series finale brings this family drama to a head. The case Hanbada takes on involves a massive data breach, and the hacker responsible is revealed to be Tae Soo-mi's other child, Choi Sang-hyeon, Young-woo's younger half-brother. This forces Young-woo into an impossible position. To win her case, she must use evidence that could incriminate her brother. This leads to a powerful confrontation where Young-woo meets her mother and asks her to be a good mother to Sang-hyeon, even if she couldn't be one for her. Ultimately, Tae Soo-mi withdraws her nomination for Minister of Justice, taking responsibility. This act doesn't fully redeem her, but it shows the profound impact Young-woo has had on her. The ending signifies Young-woo's full arrival as a professional and an individual; she no longer needs her mother's validation and has found her own family and sense of belonging at Hanbada.