A book by
Richard & Joan Ostling about
The Church of Jesus Christ of Latter-Day Saints, that is probably the most thorough and well-balanced book written about the church, certainly by people who are not members of the church.
It's about the history, beliefs, and traditions of the LDS church, their business and financial holdings, their leadership, and their phenomenal worldwide success at becoming one of the world's fastest growing religions.
I think the only way you could learn more about the church would be to actually join it yourself.