Picture, if you can, the city of Leiden back in the 1880s. Most people there were poor, working class citizens. Poverty, plague, and death were constant visitors to their doorsteps. And so was a woman the town nicknamed "Goeie Mie" or “Good Maria”. Maria was known for helping to take care of children, the sick, and the elderly. But what was not known was that this poor city was the perfect backdrop for the most prolific serial killer in Dutch history. “Good Maria” as they called her, was poisoning the neighbourhood, and her death count was reaching numbers that would shock everyone for more than a century.