Daft Harry Scrambles is two years older (13), and his inventive ideas are getting better. He and trickster sister Lou (15) hurtle through a Stone Age time portal in Harry's turbo-charged farm car, travelling from 1979 to 2079 in the hope of finding their missing, presumed dead grandpa and recovering the long-lost Queen's ruby. They discover a future perfect world about to crash into a nightmare state because scientists have genetically modified a species of giant wasp to be used for pest control inside secure crop-growing compounds. Harry finds that the monstrous stingers have learned to escape and are about to colonise the planet, but he needs a specimen to convince sceptical scientists. As the siblings battle to eradicate the monstrous species, armed only with natural weapons, they simultaneously search for their long-lost grandpa and are drawn into a crazy Victorian horse race. Finding themselves trapped in the Victorian era, Harry must find an ingenious way to repair the portal in order to save the future world from a doomsday scenario. If he fails, the siblings will never see home again... And what of their Grandpa?