Aside from being a ridiculous premise, the story folds out well and is very entertaining. If you listen based on the fact that you can believe that an entire city can of 5,000 people can remain in a secret cult and only a couple have ever escaped or left, then you'll do fine.
Notwitstanding, the story was well written a a good listen. The narrator did a fine job.
This is a terrific "beach read" with a great narrator, interesting characters and a good plot. It made me laugh out loud at times. For an enjoyable escape, pick this one.