They Live (1988)

This was a John Carpenter film that I hadn't seen before. A drifter arrives in a new city for him and he finds some work on a building site. A black guy who sees he is homeless takes him back to the shanty town where he also lives. The drifter is intrigued by suspicious activity at a church over the road. He decides to investigate and finds that there is no congregation and the choir singing just comes from a stereo PA system. All is not as it seems in this world, as he discovers when he comes across a box of sunglasses in a dumpster.
The sunglasses reveal another world within our own, a hidden world of alien invaders who live amongst us and plant subliminal messages behind every billboard, on magazines and on TV. He sees these messages starkly in black and white for the first time when he puts on the glasses. He also sees who the aliens are and immediately wants to kill them.
It's an interesting film and includes a great fight sequence between the 2 main characters. Well worth a watch if you like conspiracy theories and stories like The Matrix which challenge what you think you know about the world.