The Tindims of Rubbish Island and the Spooky Secret: The Tindims Series, Book 5

Halloween has nearly arrived, but a young witch is in a pickle. She has cast a spell and shrunk herself by mistake! When a gust of wind blows her out to sea, her best friend, a little ghost, goes with her.
They find themselves landing on Rubbish Island where the Tindims haven't met witches or ghosts before, and the witch and ghost didn't know the Tindims even existed. But Skittle, Brew, Pinch and the gang are soon helping their spooky new friends get back to the right size and home in time for their Halloween parade. And the Tindims might just decide to hold their own Halloween-Helloween party...