5,000 years ago the remote islands of Orkney were a great centre of the Stone Age World, boasting connections that stretched across the length and breadth of Britain, Ireland and beyond. And yet, despite its fame and popularity today, there is still so much about Neolithic Orkney that remains shrouded in mystery. In this documentary Tristan Hughes investigates Orkney’s enigmatic Neolithic past. Crawling into 5,000 year old tombs and digging deep into one of the greatest archaeological excavations currently underway on the British Isles, he explores this extraordinary period of Scotland's prehistory.