Do Hyun Joong, a fallen bodybuilding star, now manages a rundown 24-hour gym. Lee Mi Ran, fresh off a breakup, mistakes it for a nightclub and ends up humiliated. Hyun Joong offers to transform her life through intense training, but his brutal honesty drives her away. Still, his words hit a nerve. Can Hyun Joong change heartbroken Mi Ran's life and save the crumbling gym?

Mi-ran sets out on a gruelling fitness journey to win back her ex, and the entire gym gets caught up in her mission. Hyun-joong sees a spark of potential in her, pushing her even harder. But is it for her sake or the gym's survival? As every rep tests her spirit, Mi-ran must confront what she's really fighting for.

Mi Ran's intense training program falls apart and goes to waste after she breaks down in front of her ex-boyfriend. Despite achieving some results, including fitting into an undersized dress, Mi Ran quits the gym and demands a refund, leaving Hyun Joong frustrated. Meanwhile, Hyun Joong puts everything on the line to attract 120,000 new members to the gym, determined to turn the struggling gym around.

Mi-ran struggles with harsh criticism from her visiting mother while Rosa faces pressure to prove herself in a bodybuilding competition. As Hyeon-joong supports both women, emotional bonds deepen—especially when Mi-ran comforts a drunk Hyeon-joong. Rosa overcomes injury and self-doubt to compete, rekindling her confidence. The episode ends with a shocking twist as a child appears at the gym, calling Hyeon-joong “Daddy.”