When Archie notices his Mommy’s tummy growing, he knows something strange is happening. Not only that: Mommy’s office is suddenly completely pink! Mommy shows Archie a picture of his sister growing in her tummy, but Archie things it looks like an alien. Archie isn’t sure that he wants a baby sister. He likes cars and trains and playing cowboys. He knows for sure that he doesn’t like fluffy, frilly, and very pink things! But soon, a fluffy, frilly, and very pink bundle arrives at home. It’s his new baby sister, Olive! Big brother Archie thinks she looks like a marshmallow, and he wonders if life will ever be the same again.