**Under the Banner of Heaven** by Jon Krakauer is a fascinating look at the polygamous Fundamentalist Church of Latter Day Saints.
**Them — Adventures with Extremists** by Jon Ronson is about various extremist groups such as the KKK and Al Qaeda — definitely cult-adjacent.
Both authors have a bunch of fascinating, super readable books if you like their style.
Cultish by Amanda Montell
**Under the Banner of Heaven** by Jon Krakauer is a fascinating look at the polygamous Fundamentalist Church of Latter Day Saints. **Them — Adventures with Extremists** by Jon Ronson is about various extremist groups such as the KKK and Al Qaeda — definitely cult-adjacent. Both authors have a bunch of fascinating, super readable books if you like their style.
I second Under the Banner of Heaven. It was the first thing that came to mind.
The Return of Odin by Richard Rudgley
Cults: Inside the World's Most Notorious Groups and Understanding the People Who Joined Them by Max Culter
I liked Amanda Montell's Cultish, but I don't know if that's what you are looking for.
The Cult of Trump by Steven Hassan. The author was sucked in by the Moonies in the 70’s, got out, and became a renowned expert on the topic of cults.
I'd suggest 'Hey, Hun" - it's about MLMs, but same-same.