Despite recent progress in containing the AIDS pandemic, HIV is still a killer of epic proportion. Understanding the origins of the virus could provide crucial clues to help in the battle against the disease. The Bloody Truth accompanies an international team of researchers in their search for the origins of HIV in the hospitals and primeval forests of central Africa. They uncover HIV-positive tissue samples in the Democratic Republic of Congo that prove that HIV was first transmitted to humans in southeast Cameroon around 1908. Their efforts to salvage a mysterious medical archive containing thousands of tissue samples dating from the colonial era provide evidence on how the grounds were prepared for the AIDS pandemic. These samples shed a new and surprising light on the virus’ origins, and provide vital information on how to fight future pandemics, such as Ebola.