An all-new adventure from the much-loved, million-selling Dav Pilkey - creator of Captain Underpants! Ook and Gluk have a good life, growing up together in Caveland, Ohio, in 500,001 BC - even though they're always getting into trouble with their nasty leader, Big Chief Goppernopper. But Ook and Gluk's idyllic life takes a turn for the terrible when a scary corporation from the future invades their quiet town...