Rina’s heart didn’t pound. It sharpened. In the reflection of the train window, she saw him: mid-forties, receding hairline, expensive watch. His eyes were half-closed, a practiced mask of exhaustion. But his hand told a different story.

She didn’t turn around. Instead, she reached into her cardigan pocket and pulled out a small, metallic cylinder—no bigger than a lipstick. It was a high-frequency sonic emitter, designed to cause temporary but intense vertigo in a single targeted individual within a one-meter radius.

The passengers around them were beginning to stare. The man’s eyes darted left and right, looking for an exit that didn’t exist.