Plot: Richard Ayoade guides five intrepid celebrities - Ore Oduba, Vicky Pattison, Alex Brooker, Lydia Bright and Louie Spence - through the Aztec, Medieval, Industrial and Future zones, where they play a range of skill, mystery, physical and mental challenges to win the all-important crystals. The more they win, the more time they have in the final test - the Crystal Dome