Lewis is expecting a new sibling, and readers follow along the journey as experienced by him. While it is one of many picture books on the subject of new siblings, Farmer's approach is a childlike articulation of the fetal growth process. For example, when Lewis asks about where the baby is hiding, his mother explains that it is growing ""in a safe place--like a soft balloon that's full of warm water."" When Lewis touches his mother's belly, he thinks it feels like she ""swallowed a bunch of butterflies."" The story is mostly dialogue, but Wilson is undaunted; her soft, comforting pencil illustrations combine with a clever use of borders and designs that not only dress up the page, but convey the passage of time. It's her inventiveness and the lively, expressive characterization of Lewis that carry the book along; readers will appreciate the boy's naive forthrightness and his mother's delicate answers.