Under the Banner of Heaven by Jon Krakauer

When I started reading this book I couldn't put it down.  It is about the Fundamentalist Latter Day Saints.  They hold to the original teachings of the Mormon faith by practicing polygamy.  Some of the men have a few wives, others have had at least 40.  All of the founders of the faith were polygamists and they saw it as a gift and a requirement for salvation.
The book focuses on a family.  There were six Mormon brothers, and three of them decided to become members of the fundamentalist sect.  They became very obsessed with their new faith, and they decided that the wife and baby of one of the other brothers had to die.  The poor wife was newly married and had a baby girl.  She was upset at her husband's decision to join the polygamist sect and was opposed to his wanting more wives.  Two of the men willingly murdered them both because they believed that God wanted them to do that.
The FLDS church has made the news quite a few times over the last few years.  There have been children taken away from these compounds because they were being physically abused or forced into marriage at a young age.  There are many "lost boys" that the sect gets rid of so that there won't be a surplus of single men.  They single those boys out for small things such as wearing long sleeves.
This book is a glimpse into a subculture that is an enigma to most other people.  Though many members claim there is a lot of happiness, there are many former members that are glad to be away from that lifestyle.  I do believe that there can be a lot of love in those families, yet there are still many problems there too.