The Running Grave: Cormoran Strike, by Robert Galbraith

I don't have words for how much I loved this book. I have always been obsessed with cult stories. This might be the best one I have ever read. It just got darker and scarier and I could not stop listening. I was so lost in the story that at one point I almost started chanting. Not giving away any of the 'will they or won't they' spoilers but oh God that ending. Read it, read it, read it. I need to talk about how great this book is.

From the back

Private Detective Cormoran Strike is contacted by a worried father whose son, Will, has gone to join a religious cult in the depths of the Norfolk countryside.

The Universal Humanitarian Church is, on the surface, a peaceable organisation that campaigns for a better world. Yet Strike discovers that beneath the surface there are deeply sinister undertones, and unexplained deaths.

In order to try to rescue Will, Strike's business partner Robin Ellacott decides to infiltrate the cult and she travels to Norfolk to live incognito amongst them. But in doing so, she is unprepared for the dangers that await her there or for the toll it will take on her . . .