'The Vow' is out now, which is the documentary version of the NXIVM story. It appears there's a lot of footage from 'the inside' because a guy (who left after being a big part of it) was a filmmaker who was documenting the story and such, which gives it a pretty interesting look.
The CBC Uncover podcast about it was really good and definitely worth a listen, IMO. And if you found it interesting, then the series will probably be right up there as well.
https://www.cbc.ca/radio/uncover/unc...xivm-1.4675949