The Porter family—Tom, Kevin, and Annie—get sucked into a prehistoric alternative world while taking a family vacation. The Porters build a tree house, hook up with a few locals—Tasha, an orphaned, extra smart dinosaur; Stink, a monkey man; and Christa, another human who has lived in the since she was a little girl. The Porters must deal with living with dinosaurs and avoiding the evil, advanced Sleestaks.