It's an epidemic of staggering proportions. Thirty-six million people are infected with the HIV virus worldwide, with over 25 million of them in Africa. More than 21 million people have died of AIDS, nearly 17 million in Africa alone. THE NATURE OF THINGS with David Suzuki presents RACE AGAINST TIME, a film about the greatest challenge of the 21st century and the work of Canadian Stephen Lewis, the United Nations Special Envoy on HIV/AIDS in Africa.