It appears a litterbug is dumping garbage on Mulberry Road. Huckle decides to solve the mystery of who it is by looking for clues about the culprit in the discarded trash. In the end it turns out to be potholes that cause the garbage truck to spill its load. Giant ?footprints?, squashed car tops and broken tree tops have the Pig Brothers convinced giant robots from outer space are the cause. However Huckle proves them wrong by working through the clues and determining it was Rudolf von Flugel?s out of control hot air balloon that did the damage.