Six weeks ago a man called Louis Juneau went through a pioneering operation which gives him control over his own pain. To damp down the suffering that was ruining his life he turns a dial.

Most of us wish we could completely switch off the pains we feel in everyday life. Sometimes, like women you can see being hynotised to help deliver their babies, we can do exactly that. But the history of accidents that has befallen the remarkable family of pain-free children appearing in this programme shows pain is essential - as a danger signal. In pain clinics all over the country it's the long-lasting suffering that doctors need to control. A scientific detective story that begins with the question of why you rub an injury to make it better is now turning up clues to techniques which could realise the age-old dream - mastery over pain.