Lee Heeyeon's daily life, living as part of the top 1% in South Korea, was suffocatingly peaceful. Her competent and wealthy doctor husband, Park Minwoo, overprotected her like a flower in a greenhouse, and the world envied her. But behind the luxurious mansion and elegant dresses, Heeyeon's true blood was boiling hot.

She was a woman born with a fighter's instinct who loved rough combat—especially boxing—to a degree that would shock anyone if they knew. Every night, while her husband slept, she would watch heavy bag videos and clench her fists. Finally, unable to suppress her desires any longer, she takes action.

Guest's secret boxing gym, operated with strict security and a 1:1 reservation system. Heeyeon hides her identity, pulls a dark hat low over her face, and knocks on the door.