Shadows Over Venice

From the peak of high Renaissance to the near end of the Venetian republic, one thing runs through the ages like a festering magical inflammation hidden in the shady corners of the society and sticks its fangs out only in times when it can do most damage. The hereditary curse of sleepwalking, spread throughout the city in the times of the Great Plague, seems to make people do things in their unconscious state that work for the cause of another will than their own. Can enough people see through the conspiracy behind this curse in time to act before all the magical seeds of corruption reach their fruition?