Yang Jeongin, a young assassin, who has special powers, gets assigned to kill a politician's daughter, Azalea Nyx. But when he tries to kill her, his powers don't work on her. Intrigued, he kidnaps her and keeps her hostage, trying to figure out why his powers don't work. Months after pushing and pulling, they fall into a toxic relationship, neither one wanting to leave because of how they make each other feel. How will things play out for them?