Over 100 years ago, two great First World War warships sank in the waters surrounding Orkney, their final moments shrouded in mystery. Rod Macdonald leads an investigation into the HMS Hampshire, which sank with the famous Lord Kitchener on board. Whilst in Scapa Flow, Emily Turton examines the wreck of HMS Vanguard, looking for clues as to how this great battleship disappeared in a matter of minutes.