Why do some people love speed when some others don't? To find out Jeremy Clarkson takes his mother on a rollercoaster, rides with the British Army bobsleigh team and visits California to investigate dragboat racing. Formula One World Champion Damon Hill explains how he thrives on thrill-seeking, artificially creating pressure in situations. Clarkson learns that enjoying thrill-seeking is a result of dopamine, a hormone released by the brain to provide enjoyment and serotonin a chemical that causes a person to feel frightened. The amount of these chemicals released during an activity vary from person to person.

What makes some people better at coping with high speed than the rest of us? Clarkson interviews Formula One World Champion Michael Schumacher, World Rally Champion Colin McRae and tennis player Greg Rusedski.

How do our fragile bodies cope with high speed? Jeremy explores the risks of rapid transit, meets Cresta Run riders in St Moritz and talks to the chief test pilot of the Eurofighter.

Air resistance and how the human race tries to overcome this invisible enemy. Jeremy meets desert racers, speed skiers, test pilots, skydivers and astronauts, in an attempt to find out how nature fights back. He then attempts the Anglo-American race to break the sound barrier and experiences oxygen deprivation in pressurisation unit.

Machines which achieve the greatest speed in the world.

What speed has done for humanity and what is the best machine speed has given us? Looking to the future, Jeremy comes to the surprising conclusion that speed was a 20th century phenomenon and everything is slowing down. He also discovers that 20th century speed machines are becoming toys, which he promptly proves by getting behind the controls of a fighter plane in a dogfight with a German. Plus Jeremy reveals his ultimate favourite speed machine.