Exploring the lifestyles and history of some of the most extreme locations in Britain. Nick Crane visits the Isles of Scilly, Ruth Goodman walks the dangerous path traversed daily by the Branscombe Cliff farmers in Devon, while Mark Horton investigates the Transatlantic Telegraph service, and Hermione Cockburn learns how the fossil of a large sea creature found at St David's Head, Pembrokeshire, shaped understanding of Earth's history.