This is the expanded version of a short story called “Iphigenia in Aulis” that Mike Carey wrote for a collection of horror stories set in schools (An Apple For The Creature). To describe the premise beyond that would spoil the story for you, so I will just say that it is beautifully written and has stayed with me ever since I read it. It is deeply creepy, and yet heartwarming and, ultimately, hopeful.
(Well, OK, just a taste: “Melanie is a very special girl. Dr. Caldwell calls her “our little genius.” Every morning, Melanie waits in her cell to be taken to class. When they come for her, Sergeant keeps his gun pointing at her while two of his people strap her into the wheelchair. She thinks they don’t like her. She jokes that she won’t bite, but they don’t laugh. Melanie loves school. She loves learning about spelling and sums and the world outside the classroom and the children’s cells. She tells her favorite teacher all the things she’ll do when she grows up. Melanie doesn’t know why this makes Miss Justineau look sad.”)