firstly im sorry about my bad grammer, and the place,time,history can be diffrent. just focuc that movie.
as my father said, a guy build a castle in around 1940s. and after hes dead, a couple rent that castle idk how or from who. and that guy which make that castle around 1940s make a secret room in the house behind a mirror. so our couple renting that castle and girl discovered that room and she get in but cant get out for years. and hes bf or husband hire dedectives, cops so hes searching to her for years. but ofc he cant find. but the girl inside that room still alive coz the builder put a lot of foods water in that room.
after years she's bf bring another girl in that castle so, but new girl discovered that room too, and that girl too. but she dont let the girl out. and they talk each other with morse alphabet. one day inside girl told something to girl and convince the girl comin inside. and atracting like she dead when she came inside and shoot new girls head and left him inside the room.
im waiting for your help, thanks