Will explores the hidden pieces of history from World War Two. Wales made a huge contribution to the war effort and the remote countryside was witness to many military activities. Remnants from that time can still be found but they lie hidden. Will seeks some of them out by visiting plane crash sites on the Brecon Beacons, uncovering an old training academy on the Great Orme, gaining exclusive access to an MoD training base that played a vital role in the war and tracks down the secret bunkers of a home-based army of saboteurs.