Conversation so far:
What is Jon Krakauer's Under the Banner of Heaven?
Jon Krakauer's third non-fiction bestseller.
What is Jon Krakauer's book, Under the Banner of Heaven about?
The book examines extremes of religious belief, specifically fundamentalist offshoots of Mormonism.
What year was Jon Krakauer's Under the Banner of Heaven written?
In 2003.
Why did Jon Krakauer write Under the Banner of Heaven?
Jon Krakauer looks at the practice of polygamy in these offshoots and scrutinizes it in the context of the Latter Day Saints religion throughout its history.
What does Jon Krakauer's Under the Banner of Heaven say about Mormonism?

Question: What does this book say about polygamy?
Self-contained rewrite: What does Jon Krakauer's book, Under the Banner of Heaven say about polygamy?