1847, Vienna. Ignác Semmelweis, the short-tempered but passionate Hungarian doctor delivers babies and carries out autopsies on a daily basis whilst looking for the cause of puerperal fever, the mysterious epidemic that decimates patients in the hospital.

His boss prohibits him from conducting research into the subject and sends his right-hand man to cross him at every turn. He also threatens a young midwife, Emma Hoffmann, to spy on him. After a rocky start, the relationship between Semmelweis and Emma develops into a romance.

When Semmelweis's friend gets wounded mid-autopsy and dies with the same symptoms as the women in labour, Semmelweis discovers the cause and prevention of childbed fever. Half of his peers discredit him, yet he carries on with the fight to prove his theory at all cost.