There's nothing to do on a rainy day or so Ally thinks. But Mama says she's seen something amazing, so despite Ally's misgivings, she sets out on an adventure with her mother and grandmother. On her journey, she sees all sorts of things: dripping awnings, wet cardboard, splashing cars...but also earthworms, storm drain geysers, and oil slick patterns. And then they turn the corner, just in time to see a big crowd. What's happening?