The Core (Night Lords #2.5)

Talos and First Claw are back in action after the cataclysmic events of Blood Reaver, boarding a dangerous space hulk in search of an ancient secret. Harried by genestealers and Space Marines of the Salamanders Chapter, they must protect the traitor tech-priest Deltrian as he completes his mission. But something is hunting them through the shadows, a predator that is more than their match...
Read it because
The Night Lords are at their devilish best here, scavenging for supplies, battling Genestealers and facing the might of the Salamanders. Oh, and you might want to read Nick Kyme's Prometheus Requiem as well, to see the other side of the story.