The Couple on the Train: An absolutely compelling psychological thriller packed with suspense - Paperback

I look at where the woman was sitting. There's a scrap of paper tucked into the gap between the seats. With shaking hands, I pick it up. The note reads: Help me.

At first glance, the couple on the train look normal. She's dressed smartly, a floral patterned bag on her lap. But her hands are clenched, her fingers white. The man with her has his arm looped through hers, but not in a comforting way....