There is never a quiet day at Gwangseon Jugong Apartments! From noise complaints and suspicious neighbors to the petty villains who drive everyone mad, the incidents are non-stop. Fed up, four women join forces: Gong Miri, a sharp-eyed deduction specialist; Choo Kyungja, a former detective whose fists move faster than the law; Park Sohee, the ultimate neighborhood informant; and Jeon Jihyun, a former insurance sales star who knows everyone's business. As a single unit, they tackle the complex's chaos with a flawless division of labor. What begins as investigations into mundane apartment life soon spirals out of control, revealing shocking missing links.