At school, Penelope's teacher encourages the class to play with someone new at recess so that they can see that minds, like handprints and snowflakes, are one of a kind. Penelope chooses Eric and they have so much fun she invites him over for a play-date. Before he arrives, Penelope's Mom tells her that Eric's mind is called "on the spectrum," and so his unique preferences might be different from the ones she's used to. To prepare, they practice using quiet voices, listening with their eyes, and being flexible. As their play-date unfolds, Penelope and Eric show readers the many ways that families can embrace neuro-diversity.