Lockbox

Two estranged siblings inherit their grandmother's house after her death. While they clear out the old rooms, they become trapped behind a door with eight deadbolt locks, and the world outside the house is swallowed by unnatural darkness. The house sinks deeper into a surreal nightmare as the siblings desperately search for the keys that will return them to reality, yet their mutual anger and distrust threaten to condemn them to eternal imprisonment in a home that is not merely a house, but a trap for human souls.