It's an age-old dilemma -- what brings a livelihood to everyone in an entire community ends up killing them. Unwilling to admit to what is right there in front of them, people trust the "powers-that-be" -- they would never knowingly poison an entire community in the name of profits, or would they?? Issues specific to this time in our shared past have been repeated countless times before this specific event and will be repeated countless times in the future = creating a thematic universality to her story.
The event lasts five days and serves as a perfect antagonist. Every step the engaging cast of characters take toward their own personal goals is thwarted by the event. Page-turnability is built in as the events unfold.
Years of research and the author's own passion for the time have contributed to the authenticity of the project.
As the days pass, the situation worsens. The built-in "ticking clock" creates tension and conflict and challenges all the characters, though in the end the protagonist is affected the most and is transformed at depth.
I've always been a sucker for a great historical. Hers has got all the elements. I wish her loads of luck in writing the next draft all the way through, taking care to treat the event as a major character and plotting out each and every turn the event itself takes as it destroys everyone around it.