Michael Portillo embarks on a new series of railway adventures around the coast of the British Isles. The first stop is Siccar Point, close to Dunbar on the Firth of Forth, which was the site of an extraordinary 18th century discovery and is today a place of pilgrimage for earth scientists from across the world. Michael also visits the scene of a grisly 16th century murder, which was the stuff of myth in his childhood.