Matt Baker and John Craven head to South Wales. Matt is on the coast finding out what's being done to rejuvenate its spectacular sand dunes to prevent them from turning in to giant grass hills. Further down the coast, Matt is put to the test when he joins a local college rugby team who use the dunes as an outdoor gym. Further inland, John Craven unearths a tale of deception. In 1944, seventy German Prisoners of War tunnelled their way to freedom from a prison camp in Bridgend. It was the biggest escape attempt on British soil. John discovers how they managed to do it right under the noses of the guards and he helps to create a 3D model of the escape route. He also meets a woman whose family aided the capture of two of the escapees. Elsewhere, Tom's on the trail of our fastest growing source of energy - bio-mass and Adam's investigating a winter crop.