After a fall and a blow to the head, Lyra begins to have hallucinations that she's a young human girl in mental hospital. As she flashes back and forth between the two, medical personnel in each do their best to cure her of her delusions. But as the day wears on Lyra begins to question which world is real and which one is only a mental construction. How can she pick one world, when they both seem so convincing? And what happens if she chooses incorrectly?