The Last Church: The Horus Heresy Series

Some flaws, but mostly decent story that 40k fans will want to listen to.

The audio book is about 90 minutes long. What it does exceptionally well is tell the story of the last church on Terra/Earth. It is a extraordinary in-depth philosophical debate between one priest's religious faith and the Emperor's deadly pursuit of unifying humanity under a secular banner. It is absolutely worth your time. The ending is truly enlightening.