The series begins with a woman named Madhu moving to Delhi from Gwalior. She has come to Delhi to be with her boyfriend and to get a fresh start after getting sexually assaulted at her college annual day by unknown masked men. She is helped by her friend Bella and her boyfriend Nakul. She moves to a rundown working women's hostel where she is allotted the room 333 and is met with extreme hostility by the other girls in the same wing, who never leave the hostel to go out. They warn her to not move to the hostel and leave while she can. She feels the presence of something supernatural and brushes it off while suspecting Nakul of being one of the men who assaulted her. Madhu starts to doubt her own sanity as strange things start occurring in the hostel room.