The team explores the Welsh coast. Nick Crane investigates evidence that a devastating tsunami hit 400 years ago, and finds out why scientists planning a trip to Mars find the local landscape a surprisingly good stand-in for the red planet's surface. Alice Roberts tests the claim that the world's first powered flight was made by a Welsh carpenter seven years before the Wright brothers and Dick Strawbridge reveals how, in 1947, a man on holiday to Anglesey came up with the design for a new car that would conquer the world - the Land Rover.