Europe, late 19th century. Antibiotics have yet to be invented, and germs take a death toll that lets the number of murders appear negligible. But when a cholera victim is found floating in one of London's drinking water supplies, Dr Anton Kronberg - England's best bacteriologist - is called upon to investigate. He crosses paths with Sherlock Holmes. The detective immediately discovers Kronberg's secret -- a woman masquerading as a man in order to practice medicine -- a criminal deed that could land her in prison for years to come. The two highly analytical minds provoke and annoy each other at once. Eventually, they must team up to unravel a spiderweb of murder, espionage, and bioterrorism that spreads across continents.