Crazy Dave's brainy niece Patrice, neighbourhood daredevil Nathan Timely, and a batch of bold plants discover 'Zomboss's Secret Plan for Raising a Zombie Army Underground and Then Swallowing the Entire City of Neighborville Whole!' A rare Boom Boom Mushroom must be found in order to save the humans above ground Crazy Dave and a strange new animal friend (maybe stranger than Dave!) search for the powerful mushroom, while Zomboss puts his plot for subterranean subterfuge in motion!