Idol singer Eun-chae, on the verge of being expelled from the industry due to a scandal, suddenly receives news of her father's death — along with an inheritance: a heavily indebted taekwondo gym. Hee-chan, a former athlete who quit after an injury, is now an instructor at the gym. Together with his hobby-class students — each carrying their own story — he dedicates himself to training with the goal of winning a national championship. When Eun-chae returns to her hometown intending to sell the gym, her ex-boyfriend, Soo-yeol, a second-generation chaebol, makes her an irresistibly dangerous offer... Can Eun-chae, Hee-chan, and the hobby-class students overcome the endless hardships of reality and write a brand-new chapter in their lives?