Every day, in a little house in a little town in the middle of a big place, a girl stands at her window and waves to the engineer of the train that passes on the nearby tracks. The engineer waves back and his wave and her wave together make a home in her heart. The little girl is curious about the engineer, about where he came from and where he goes. Which makes her wonder if she might go away, too, some day. This beautiful picture book explores the magic of a connection made between strangers, while also pondering the idea of growing up, and what might lie beyond a child's own small piece of the world.