Patient Zero is a stewardess, stricken with what she thinks is chickenpox. She goes to ground in a Montreal hotel. A few weeks later she’s back on the job, unaware of her role in an impending public health catastrophe. Pandemics have killed more people in history than all wars combined. They are unpredictable — and inevitable. “Outbreak: Anatomy of a Plague” juxtaposes a fictional 21st century scenario against the story of the 1885 smallpox epidemic vividly evoking a modern city under siege.