Haze (2005)

A man wakes up to find himself locked in a very tiny, cramped concrete corridor, in which he can barely move. He doesn't remember why he is there or how he got there. He has a terrible stomach injury and is slowly bleeding to death. He begins to edge his way along the narrow maze-like corridors, only to see other people undergoing their own horrible tests though holes in the walls. Unable to find a way out, he finally gives up on the struggle and gives in. Barely clinging to his sanity he creeps forward with the last ounces of his strength and meets a woman in a place full of floating corpses. The man and the woman both try to recall where they came from, but their memories are so uncertain that they are not even sure they want to return. The man insists on giving up but the woman maintains that it was not her fault and refuses to give up. Reluctantly he agrees to help her, as she attempts to swim past the corpses. Neither of them can imagine the incredible end to the journey.