The train was half-empty. I took the window seat and tried to read, but I wasn't the reading type anymore. I was the watching type.That's when she sat down across from me.Middle-aged. A linen dress that cost more than it looked. Her hair was pinned up dark with silver threads, held back like she was keeping something in. Amber bracelet. Matching earrings. White shoes, scuffed. Her hands gave her away—long fingers, one small scar on the left wrist. The kind you get when you know exactly what you're doing and do it anyway.She was trouble. The kind that looks like class."This seat taken?" she asked."Help yourself."But I was watching her. She shifted every minute. Nervous. And nervous people make mistakes.