Neil Oliver discovers the remarkable story of the World War II freedom fighters who risked everything running the Shetland Bus, a series of top secret missions into Nazi-occupied Norway. One of the worst environmental disasters hit the coast at Garths Ness in 1993: Braer, an oil tanker, ran aground and spilt 84,000 tonnes of toxic crude oil into the sea, polluting Shetland's coastline and wildlife. Neil takes a ride on the world's shortest scheduled flight, between Westray and Papa Westray, which provides an important link to these small communities. Mark Horton explores dangerous waters when he joins one of the world's most sophisticated survey ships on a mission to find the uncharted hazards that wreck unwary vessels in Orkney.