Overview:Over 230 islands make up the Northern Isles - The Shetland and Orkney. These magnificent islands are made up of rock stacks, secret inlets and spectacular scenery, surrounded by sometimes extreme sea and weather conditions that have shaped these islands. Neil Oliver joins an expedition climbing the Old Man of Hoy in Orkney and finds out about the Second World War freedom fighters who risked their lives running the "Shetland Bus". Miranda Krestovnikoff goes in search of an elusive octopus, Nicholas Crane finds evidence of a tsunami that devastated Britain 7,000 years ago and Alice Roberts unearths a mysterious skeleton that reveals more about the lives of ancient Shetlanders.