Charley Boorman returns for a new four-part series and a brand new adventure, exploring the USA. Charley starts off in Hawaii before heading up to Alaska, flying to Boston on the east coast and travelling west across mainland America to Los Angeles. Along the way he searches out the most extreme activities in which to immerse himself, such as crossing live volcanoes, squeezing through narrow caves, setting up camp underground and abseiling down a waterfall.