Series telling the incredible stories of the guinea-pig doctors who transformed medicine. Presenter Dr Michael Mosley explores the curious and sometimes fatal ways in which pioneering doctors laid the foundations of modern medicine by experimenting on themselves. In this first episode, Dr Mosley charts the development of pain-free surgery. He starts with the 18th century chemist Humphrey Davy, who inhaled up to 50 pints of laughing gas a day and yet missed its true significance. Conman-turned-dentist Dr William Morton slept with a skeleton by night and experimented with ether by day, 19th century Scottish national hero James Young Simpson's reckless enthusiasm for chloroform led to numerous deaths and Sigmund Freud's experiments with cocaine transformed anaesthetics. Mosley also undergoes some of the historical experiments himself and meets researchers who are continuing the tradition of self-experimentation today.