The Uninvited Guest (2005) on Netflix

In the dark corridors of Félix's house, an intruder is hiding. Is he real, or is he a manifestation inside the obscure maze of his mind?

Recently separated from his wife Vera, Félix a young architect, embittered, he finds it difficult to trust again, and being fragile and emotionally unstable, he lives secluded in his now deafeningly silent and vacant house. Unexpectedly, in the middle of the night, a stranger knocks on Félix's door desperately in need of a phone call, and without giving it much thought, hesitantly, he lets him in, however, after a while, when the man is nowhere to be found, paranoia will strike. Has he left or is he still somewhere inside the house hiding? In the following days, as unexplained sounds and strange noises banish the mansion's silence amplifying the tension and the uneasiness, Félix will question his very reason as he will gradually begin hearing and seeing things in the dimly lit corridors. Is the intruder indeed real, or is he a manifestation inside the obscure maze of Félix's mind?

—Nick Riganas

What if ... you let a stranger into your house to use your phone, but while you've been patiently waiting in the kitchen, he just disappears ... or does he? Félix, an architect who has just split up with his girl-friend and inhabits a huge mansion in Barcelona, finds out how many hiding places there really are in his house. But are there enough to hide another person, a strange parasite of living space? Or is Félix really going insane?

—sweet.smartie