The Judges, In Their Hunger (Angels of Death, #10)

On Sendennis, Imperial rule has fallen. Governor Bellasun cowers in fear of the new rulers of the world, the judges of the Flawless Host, fallen Space Marines whose appetite for luxury exceeds even his own. But Imperial forces are on their way in the form of the savage and bloodthirsty Space Marines of the Carcharadons. Read it because
It's a Chapter who you don't see in prose often, in a tale told in a most unusual way.