After attending a medical presentation of the eminent Dr. Robert Koch demonstrating that tuberculosis is a bacterial disease, Ehrlich is able to obtain a sample of the isolated bacterium.

After an intense time of research and experimentation in his own lab, paired with a portion of luck and thanks to the empathy of his wife, he is able to develop a viable staining process for the microbe.

Dr. von Behring (who had earlier told Ehrlich to give up his pipe dreams of cures by chemicals), is called by the defense to denounce 606.

Ehrlich is exonerated, but the strain and stress from the trial are too much for his weakened body and he dies shortly thereafter, his final words being counsel to his assistants and colleagues on the risks involved in advancing medicine.

However, Warner Bros. had already produced a series of medical biographical films during the 1930s, including the Dieterle-directed The Story of Louis Pasteur (1935) and The White Angel (1936) about Florence Nightingale.

Surgeon General Thomas Parran Jr. had in late 1936 begun a syphilis control campaign to get the public to consider it to be a medical condition and not a moral failure, suggesting that a film on Ehrlich' life would be acceptable.

[2] However, the Nazi regime in Germany had systematically expunged all memory of Ehrlich from public buildings and street signs and censored books referring to him.

A memorandum circulated by the studio bosses stated with regard to the forthcoming Ehrlich movie: "It would be a mistake to make a political propaganda picture out of a biography which could stand on its own feet."

In addition, the original version of the deathbed scene was changed so that Ehrlich no longer would refer to the Pentateuch (books of Moses in the Bible).

However, Hal B. Wallis, Warner Bros. head of production, while advising caution, wrote to the PCA that "to make a dramatic picture of the life of Dr. Ehrlich and not include this discovery [the anti-syphilis drug Salvarsan] among his great achievements would be unfair to the record."