[1] A boy named Tom is playing make-believe by himself when his dog, Rex, chases his neighbour Lucy's cat out of the house.
Tom then meets Professor Crankwhistle, a friendly inventor with a flying airship, and they follow the pirates to their hideaway on Fire Island.
A fight ensues, during which Lucy sabotages their gunpowder and the bunyip damages the pirate ship, forcing them to retreat to Fire Island.
Professor Crankwhistle tows the Queen's longboats with his airship, and together with her soldiers they head to Fire Island and attack the pirates while they're unprepared.
Tom and Lucy are dismayed that they can't prove their story, but the bunyip is on top of the tree and laughs at the adults for their skepticism.