In this Fierce Earth special, Clare and Leo head to Death Valley in California which is officially the hottest place in the entire world, with record-breaking temperatures of a sizzling 57 degrees centigrade. The pair endure a special test to work out what colour clothing is the best to wear in heat; Clare finds out what it's like to go to school in the world's hottest place; Leo becomes one of the first people in the world to climb the hidden canyons. Later, in the intense heat, Leo completes a section of the Badwater Ultramarathon, a race five times longer than the London marathon.
