THE wonders-and terrors-of the unknown have served as a challenge to mankind since the beginning of time. This is the absorbing story of thirteen scientists who met that challenge, who blazed a path through the darkness of ignorance, who experimented and failed-and tried again.

These courageous pioneers faced dangers that would terrify the ordinary man. Theirs was a world where deadly assassins lurked in the form of disease-carrying microbes. Some fell victim to these invisible enemies but others fought on and conquered. These great men and their relentless struggles provide one of the most gripping stories the world has ever known.