In a world where love teeters on the edge of obsession, Seongcheol and Jeonghan share a bond so consuming that nothing, not even the threat of death can break it. United by their undying devotion and their only weakness, their adopted son Mingyu, the three form an unshakable family that Seongcheol fiercely protects. As one of the nation's most powerful and feared men, Seongcheol's love is both their shield and their cage. No one is allowed near his husband or son, his family belongs solely to him.
But their carefully controlled world is shattered when Seongcheol suffers a life-threatening accident, leaving him unconscious and uncertain to recover. Heartbroken, Jeonghan clings to Mingyu, lying to the boy that his father is away on business to shield him from the devastating truth.
Their fragile reality takes a dangerous turn when Joon, a man who eerily resembles Seongcheol, moves in next door. Mingyu, desperate for his father's presence, mistakes Joon for Seongcheol, igniting a storm of emotions in Jeonghan. Despite Joon's willingness to help, his jealous girlfriend targets Jeonghan and Mingyu in a fit of rage, unleashing a chain of events that reveals just how far Jeonghan will go to protect his son.
When Seongcheol awakens to find his son calling another man "Dad" and his beloved Jeonghan growing close to someone else, his jealousy spirals into a darkness even he can't control. Fueled by possessiveness and a terrifying need to reclaim what's his, Seongcheol unleashes a vengeance that will leave no one untouched.
In this gripping slasher tale of love, obsession, and family, how far will Seongcheol go to ensure that his family remains his and his alone?