Jaerim An, known to the underworld as the "Executioner," is the most fearsome and ruthless supervillain in existence. Despite his terrifying secret identity, he is utterly devoted to his ordinary, sweet civilian girlfriend and wants nothing more than to marry her. However, the path to the altar takes a chaotic turn at their formal pre-marriage family meeting when she introduces her relatives—her grandfather, father, mother, older brother, and uncle. To Jaerim's absolute horror, he realizes his soon-to-be in-laws are the members of the Hannyeong family, the most powerful and legendary superhero clan in the nation, whom he has spent his entire life fighting. Trapped in a high-stakes double life, Jaerim must keep his identity a secret, act like a model son-in-law, and survive awkward family dinners with the very heroes who want him dead. To complicate matters, the hero family mistakes his dark aura and strange habits for those of an eager, aspiring rookie hero!