Robbie Coltrane continues his journey through 20th Century engineering by examining the engine that changed the course of motoring and military history: the supercharger. Travelling from the wilds of Scotland to the famous N?rburgring race track in Germany, Coltrane charts the development of the supercharger from its motor-racing origins to the vital role it played in the battle for air supermeacy in World War II and beyond.

• Robbie Coltrane