The third episode in the series is set against the golden age of streamlined steam and the rivalry between the East and West Coast railway companies as they fought to transport passengers from London to Scotland in the shortest time possible. LMS on the West Coast produced the Coronation Scot, while on the East Coast, LNER retaliated with the legendary A4 Pacifics - sleek and powerful, they were the fastest trains in the world. Speed sold seats, and competition pushed machines to extremes. In 1938, LNER's Mallard reached 126 mph, a world record for steam that still holds today.