The Plagues of Breslau

Every day at 6 pm a serial killer kills a different person. Police officer Helena Rus decides to find the killer by researching about 18th century history of the city.
Every day at 6 pm a serial killer kills another person. Police officer Helena Rus thinks the killings are done by one man only and decides to reveal the killer's identity by getting back in 18th century history of the city.