Paolina Barthes is a young woman of remarkable intellectual ability - a genius on the level of Isaac Newton. But she has grown up in isolation, in a small village of shipwreck survivors, on the Wall in the middle of the Atlantic Ocean. She knows little of the world, but she knows that England rules it, and must be the home of people who possess the learning that she so desperately wants. And so she sets off to make her way off the Wall, not knowing that she will bring her astounding, unschooled talent for sorcery to the attention of those deadly factions who would use or kill her for it.