Bertram Phillips's M.I.N.D. Machine throws him back to southern California's Jurassic period, and this time it also throws real dinosaurs forward into the halls of Wetherford Junior High! Bertram's only chance of setting things right again is to accept the help of J.D. "Judgment Day" Harms, the biggest bully in the eighth grade and the second-smartest student after Bertram. But J.D.'s own plans aren't pretty, and they may change the future forever.