Butterfly on the shoulder

The theme of this film is quite straightforward : a man struggling alone against unknown forces. The man is a perfectly ordinary sort of person. He has a wife and a job. He lives in a normal, straightforward, ordered world. But his life is turned upside down in the brief space of two days because of a door which isn't properly shut. A trifling event which literally projects him into another world. This other world exists, side by side with ours, beneath ours, it's inhabited by flesh and blood people, who talk and die like us. The adventure begins when this ordinary man tries to work out what is happening to him. Why should he have been chosen? Why is he being followed, observed, beaten? Why is he being pressured to yield up something which he doesn't have.