The Cause of AIDS: Fact and Speculation, produced at MacLean Hunter Cable TV by award-winning Toronto journalist Colman Jones, features interviews with key figures in the HIV debate, such as Michigan State university professor Robert Scott Root-Bernstein (author of "Rethinking AIDS"), New York AIDS physician and researcher Dr. Joseph Sonnabend, and independent investigator John Scythes of Toronto's Community Initiative for AIDS Research. Also featured are Dr. Norbert Gilmore from Montreal's McGill AIDS Centre, American syphilis expert Dr. Edward Hook, Toronto Hospital's Dr. Richard Fralick as well as leading activists, educators and people with AIDS, including the late Michael Callen.

Part 4, Syphilis in the AIDS Era, looks at how the advent of antibiotics and the emergence of the gay liberation movement in the last few decades has affected the diagnosis of syphilis, particularly the blood tests - now under increasing scrutiny in people with HIV - and examines various treatment options, including both penicillin and immune-based therapies. The series concludes by assessing the response to this debate by the AIDS community and reflects on the politics of science and sex.