The Real Villain Revealed: Han Ji-yong is a violent sociopath who secretly finances private underground fight clubs where men beat each other nearly to death for his personal amusement. He systematically gaslights Hee-soo, attempts to isolate Ha-joon, and orders hits on those who threaten his corporate rise.
The Co-Mother Alliance: When Kang Ja-kyung's identity as Lee Hye-jin (biological mother) is exposed, Ji-yong tries to pit the two women against each other. Realizing his toxicity, Hee-soo and Hye-jin form a silent alliance. After Hee-soo suffers a miscarriage from the shock of Ji-yong's lies, she keeps the loss secret from Ji-yong to execute her plan to escape Hyowon with Ha-joon.
The Murder at Cadenza: On the night of Soo-hyuk’s engagement party, butler Kim Seong-tae lures Ji-yong to the basement bunker with gas under Jin-ho's orders, but loses his nerve and turns it off. An enraged Ji-yong encounters Hee-soo on the upper stairs of Cadenza and begins strangling her. Head Maid Joo Min-soo sees Ji-yong choking Hee-soo to death and grabs a heavy fire extinguisher, striking Ji-yong on the back of the head. The blow causes both Ji-yong and Hee-soo to fall over the balcony railing; Ji-yong dies instantly from the fall, while Hee-soo survives with injuries.
The Cover-Up and Amnesia Strategy: Jung Seo-hyun orchestrates a cover-up to protect everyone. She sends Head Maid Joo into hiding and instructs Hee-soo to feign traumatic amnesia. Hee-soo pretends she cannot remember anything from her marriage to the night of the fall. Despite Detective Baek’s strong suspicions, the case is officially closed as an accidental fall/suicide.
Resolution & Six Months Later: Jung Seo-hyun is appointed CEO of Hyowon Group, publicly embraces her authentic identity, and contacts Suzy Choi to reunite. Seo Hee-soo leaves Hyowon Group with Ha-joon, returns to her acclaimed acting career, and co-parents with Lee Hye-jin. Han Soo-hyuk renounces succession rights and marries Yu-yeon.