The British biological warfare laboratory established at Porton Down in 1940 occupies a special niche in the history of science and war. It has been a restricted and highly controlled space for the production of secret knowledge, and it has provoked sustained and enduring public controversy since as early as 1948. It has operated at the margin between the public and the secret, between offensive and defensive knowledge of pathogens, and between military research and health-care research. True and untrue rumors of novel diseases, infected research animals, accients, suspicious deaths, and long-term contamination have focused on the facility for decades. The laboratory's staff scientists have also published many hundreds of respectable papers in scientific and medical journals. Porton Down is a place where the contradictions of twentieth-century biomedical science are clear and compelling.