Chris reveals the secrets held in the DNA of Orkney's unique vole species. Neil explores some of the tombs and monuments on the Islands, Andy climbs a famous sea-stack and Shini examines a weighty problem.
Andy and some local volunteers build a boat made of just willow and cow hide and set out to cross the dangerous Pentland Firth as the ancient Orcadians would have done. Chris Packham goes in search of whales.
Andy dives beneath the waves in search of the inspiration for the first stone circle. Shini tests the technology behind a Bronze-Age sauna, Chris and Neil spend the night on an abandoned island looking for clues as to why cultures change.