The adventurous discovery of the bacterium of bubonic plague (Yersinia pestis), by Alexandre Yersin and Shibasaburo Kitasato during the third pandemic in Hong-Kong (1894) is presented. The two young scientists met at the peaks of both a terrible epidemic and an amazing scientific conflict. The story takes place in a city devastated by the plague, in the framework of the French-British colonial struggles and a variety of personal ambitions. The role played by the Scots colonial physician Lowson, the scientific alliance between Britain, Japan and Germany, and their struggle with the Institute Pasteur and the French Academy of Sciences, provide the backdrop to this discovery. For most of the next 100 years, the conflict in the scientific community was to continue through a second round on the official nomenclature and the final taxonomy of the Yersinia pestis.