The movie is about a woman and her son that move into this house that has been divided into two apartment. The owner of the house lives in the other side and he has a son. The woman later discovers that there is hidden secret passages inside the walls and the owner son had been drugging her up and coming through the walls into her apartment watching her sleep and playing with her son in his closet...

Someone Is Watching (2000 TV movie)
Starring Stefanie Powers
IMDb synopsis:
Cory is a young boy who has just moved into a new house with his foster mother. He develops a relationship with an "imaginary" friend who lives in his closet. No one believes him until people start dying violently and the imaginary friend becomes all too real.

Someone Is Watching (TV Movie 2000) - IMDb