As the sun rose higher, the September day grew warm and sunny. Rachel angled her broom upward. Up higher, it was not the Island of Roanoke she saw beneath her—with its virgin forests, its open campus lawns, its august stone buildings, and its rocky tor—but Bannerman Island, the obscuration set in place to keep the mundane world from troubling the school. Bannerman Island was small and wooded, with an old mansion and a ruined castle. It was deserted.

Rachel put her broom into a hover and closed her eyes. She thought back on the last few seconds. The real island spread beneath her in her mind’s eye. The ruined castle and the old mansion were still there, but there was a much vaster tract of buildings and forest between them.

Now, to see if she could accomplish a trick her mother had secretly taught her. She opened her eyes and gazed down at the false image of Bannerman Island. While looking down, she simultaneously thought back a second. The illusion popped like a soap bubble. Rachel caught her breath. She could now see the real island.

Letting go of the handlebars, she clapped her hands, delighted. Obscurations might fool the eye, but they could not fool her perfect memory.