The Mushas, Puffy and Stink, trick Tom and Twigs into carrying out their mischievous plans to mess up Treetop Castle. If Treetopolis and his friends are to be saved from a mucky muddle, Tom must summon the courage to question things that he knows in his heart are not to be trusted. As the stinky slime flows, he needs Big World Magic help from the audience to save his friends, tidy up the town and foil the plans of his fiendish fungus foes.