The first time Erin cast a spell, she forgot her father’s face.

It happened during the entrance exam at the academy of magic. The other candidates needed only to light a lamp. A breeze from a childhood afternoon, the smell of a particular dinner—any small memory could buy them a moment of flame. Erin offered every memory she could think of, but her wick stayed black. At last, the examiner told her she had been born without magic.

As she left the classroom, a boy in blue robes caught up with her and asked why she was crying. Erin could not answer. All she knew was that a hollow had opened in her memory. Father was written around its edge, but she could not remember who was meant to be inside.

The next day, the academy sent her to inventory the old towers. The city had twelve towers of magic, each bearing a name and each holding memories spent by spellcasters. She carried her keys across the square and counted the towers once. She reached thirteen.

The last tower stood behind the clock tower. Tiny white flowers grew between its bricks. It appeared on no map, and passersby seemed unable to see it. There was no lock on the door, only a brass plaque: Lost and Found.

Erin went in. There were no wands or incantations, only drawers beyond counting. The nearest bore her name. Inside was a photograph of her at seven, perched on a man’s shoulders. She recognized her own smile. She still could not recognize his face.

Behind her came the sound of a turning page. An old man sat at a counter, speaking without looking up. “Don’t take it just yet. If I return the memory, that lamp will go out starting yesterday.”

“But it never lit yesterday.”

The old man finally raised his head. His expression changed. He looked past her, through the open door, as blue fire flared along the spires of the twelve towers, one after another.

“Then,” he said, closing his ledger, “someone else paid your price.”