Rosie lives in a playhouse with her colourful group of friends. Together they embark on adventures as they learn the meaning of true friendship. It's a sizzling hot day and Rosie is helping Will to deliver bottles of bozberryade. When the go-speeder gets stuck in mud, Will sends out a message in a bottle. The friends don't realise the message is from Will and it's the beavers - Mat and Nat - who finally come to his rescue.