Dr. Paul Ehrlich was the German physician who developed the first synthetic antimicrobial drug, 606 or Salvarsan. The film describes how Ehrlich first became interested in the properties of the then-new synthetic dyes and had an intuition that they could be useful in the diagnosis of bacterial diseases. After this work met with success, Ehrlich proposed that synthetic compounds could be made to selectively target and destroy disease causing microorganisms. He called such a drug a "magic bullet". The film describes how in 1908, after 606 attempts, he succeeded.