The Room (Das Zimmer)

A young woman and young man, strangers to each other, show up to house-sit the same vacant house. They are allowed free reign, except they are forbidden from entering one locked room. Strange things begin to happen, and Polaroids of them in various stages of undress appear around the house. Both are haunted by inner fears from their past, yet strangest of all, neither decides to leave the house when it becomes clear they're being watched and manipulated. And while they go up to the locked door several times, neither has the wherewithal to break in and see just what's behind it.