I slung my bag over my shoulder and pushed through the hallway, trying to ignore the crowded chaos of students all around me. My locker was just ahead, and I fumbled with the combination as my mind raced. I had barely gotten through the door of the school when I felt it—a nagging tension, like I could already sense trouble waiting for me.

I twisted the dial, feeling my fingers slip once, then again, until finally the locker clicked open. I shoved my books inside, but my hand brushed ...