Life among the cavefolk isn't easy. Everything they do is gross, from eating raw meat to skipping showers. Thirteen year-old Frank, lost in their strange world and cut off easy pizza and other modern conveniences, tries to invent fire, but his good intentions might just blow up in his face. For one, smoke inhalation can be deadly. Who'd have thunk proper ventilation was so vital to cave living? Then there's that rival clan, plotting to develop a firearm... Throw in a tribe of bloodthirsty bunnies that kill with cuteness, and you've got another zany, zippy adventure in prehistoric times.