Everybody's favorite Wombat is back, and he's desperate to cool down! Winston wants to play outside, but it's SO hot. Luckily, his mom comes up with a great idea: They can play in the sprinklers! Together they jump and laugh and play in the cool water under a hot summer sun, and then things get even better. There's a rainbow! Right there in the mist. But where did it come from?

With the help of his mom, Winston learns why rainbows appear when there's mist in the sun, and how it's just like friendship and love-something miraculous that you can feel and enjoy, even when you can't catch it in your hand.