Darren Stonkadopolis and his gutsy friends made history when they saved Buttzville by using their fantastic flatulence to face down evil. But now can they hold their own against the foulest beast ever to roam the earth?

When the fourth grade class takes a field trip to the Natural History Museum, Darren cuts more than cheese—he accidentally melts a petrified tar pit and unleashes the beast trapped inside. Now Fartasaurus Rex, the only animal to hunt using the strength of its stinks, is loose in the streets. It's time for the Fart Squad to get prehistoric on the malodorous monster before the whole town becomes fossil fuel!