Professor Darwin and Mo have gone to visit an archeological dig site, where the professor's old friend and mentor, Dr Robert Cope, has found an exciting new way of studying dinosaurs.
When the two of them go missing, the rest of the Heroes go to investigate. As well as getting into a spot of T. rex trouble, they find that palaeontologists aren't the only people that have been travelling into the past - but who are they and what are they doing there?
