The advance of medicine depends inevitably on the testing of experimental procedures on human volunteers from either the healthy or the sick. Yet such procedures are often dangerous, and may not be of direct benefit to the subject. NOVA examines how individuals' interests are safeguarded, and asks, under what circumstances experiments should be conducted on children.

When Paul Kammerer committed suicide in 1926, it was taken by most of his fellow biologists as a tacit admission of guilt that he had faked his experiments purporting to show the inheritance of acquired characteristics. Arthur Koestler joins NOVA in an in-depth examination of Kammerer's infamous experiment.