it happens in a heartbeat song

My father's adopted daughter was only locked in the cramped storage closet for around fifteen minutes, yet he punished me by tying me up and throwing me inside. He even sealed off the ventilation with towels. "As Wendy's older sister, if you can't take care of her, then you should also experience how scared she was," he declared coldly. He knew I was claustrophobic, but my desperate pleas for mercy, my terror, were met with nothing but heartless reprimands. "Let this be a lesson on how to be a good sister." As the last sliver of light disappeared, swallowed by the oppressive darkness, I struggled helplessly. A week passed before my father finally remembered my existence and decided it was time to end my punishment. "Let's hope this week served as a good lesson for you, Jennifer. If this happens again, you will no longer be allowed in this house." He would never know that I had already taken my last breath in that suffocating room. My body had begun to rot in the darkness.

Kang Do-hyun chooses an ordinary life as a taxi driver to avoid inheriting his father’s family business. One day, he happens to rescue Cha Eun-seol, who is fleeing a chase and has accidentally taken the wrong medication. After a one-night encounter, they part ways and return to their separate lives. Four years later, a stylish CEO shows up with a child and proposes marriage to Do-hyun. After registering their marriage, Eun-seol faces pressure from her parents to abandon the child, but Do-hyun appears and protects both mother and daughter. As her company falls into crisis, Eun-seol attends a family banquet of Taegang Group—the most powerful conglomerate in Country A—to secure a 10-billion-won investment, unaware that the chairman is actually her husband’s father. At the banquet, despite pressure from her former fiancé Gu Jung-tae, Do-hyun’s father protects his granddaughter Kang Rumi and makes his presence known, yet he can only approach her as a “grandfather” without revealing his true identity. As time passes, Do-hyun and Eun-seol grow closer. However, after failing to secure investment, Eun-seol risks both her company and her board position by making a dangerous bet with her father, Cha Myung-hwan. At this critical moment, Do-hyun seeks out his father, accepts the responsibility of becoming the heir, and begins to take action himself. In the end, at a press conference, the capital and influence Do-hyun has prepared turn the situation around. Eun-seol not only saves her company but also secures full ownership, achieving both love and success.