Sleep Tight(2012)

César has a secret: he enjoys creating pain, hurting people all around him. And his job as a doorman in an apartment building is the perfect cover, putting him in position to learn the habits, routines, secrets and weaknesses of the building, all without arousing suspicion. When a new neighbor moves into 5B, he finds her smiling ear to ear, happy as can be, all the time. In her, Cesar finds his new objective, which soon becomes an obsession: to make her life miserable. Only Cesar's game soon gets more complicated and unpredictable than he had originally planned.