Intermission was over, patrons reentering the theater, when I set foot on the plush carpet at the bottom of the stairs. I pushed past a number of them on my way to the outer doors, desperate for a breath of fresh air. I staggered through a cloud of cigar smoke and into the cool London night, gasping for something that had nothing to do with oxygen.

A battle raged inside me. I found a low stone wall and collapsed on it while my magic, the magic I'd been born with and had ...