A new season is about to begin at the Shortbread family's circus! The big-top is ready and everyone is excited to get started. But as the shows begin chief clown Mr Birdcage is in a bit of a pickle - none of his hilarious props seem to be working! When budding detectives Billy, Fern and Joe get on the case to investigate, they soon discover that the props have been tampered with! But who would want to sabotage Mr Birdcage and why?