Soul Hunter by Aaron Dembski-Bowden

The Night Lords are one of the most feared Legions of Chaos Space Marines. Remorseless hunters & killers, they relentlessly battle the Imperium of Man to avenge the death of their Primarch Konrad Curze. Their dark crusade takes them to the world of Crythe Primus, where they will fight Imperial forces to claim the planet.

Up till now, Dan Abnett's Prospero Burns was my high-water mark for 30k/40k ficiton. Soul Hunter is really good. It may even better than Prospero Burns and I'm a Space Wolves fan.

In a sense, Dembski-Bowden pulls of a Soprano's maneuver with Talos and the Night Lords. You know they're the bad guys, but inch by inch you get pulled into seeing the Imperium and the long war through their crimson lenses. It's not just Octavia who's on their side by the final chapter.

It's a really clever bit of writing. Especially in regards to CSM politics. They could easily be slavering morons, but even Abaddon is depicted with more nuance than you'd expect. The Exalted in particular–well I really didn't see his arc coming to be honest.