The adventures of Frank and Buster, two intrepid young koalas who fly around the Australian outback in their yellow plane, on a special mission to help other creatures in need. While Archie is showing Josie his automatic tennis-ball lobbing machine, the machine starts going awry and firing balls everywhere. Josie notices that a piece has fallen off the machine, but Archie doesn't listen to her. The Koala Brothers remind Archie to listen to others - even those with quiet voices.