When Sarah and her younger brother Charlie go to stay with their grandparents, it rains for days. At first, they have fun exploring inside the big, old house, but eventually they want to explore outside, too. "Where does the rain come from?" Sarah asks her grandfather, Big T. He promises to show her once it stops raining.

When the storm passes, Sarah, Big T., Charlie and Keeper the dog go exploring. They jump in puddles, draw a puddle map and finally find the biggest puddle in the world!

Mark Lee's lively story is an introduction to the water cycle for young readers. Nathalie Dion's soft illustrations show the fun, loving relationship between Big T., Sarah and Charlie.