Halo: Parasite's Wake - Tim Lebbon

An original novel set in the Halo universe-based on the New York Times bestselling video game series!2552. As the planet Reach falls to the alien alliance known as the Covenant, a lone human ship-the UNSC Pillar of Autumn-fled into slipspace and has arrived at a place that could change the course of this decades-long war. An ancient, mysterious ringworld: Halo. With human forces scattered across the surface of this immense alien construct, Staff Sergeant Marvin Mobuto must now lead his fellow crewmates-survivors from the ship's brig-back to the Autumn's crash site to rally and regroup with their allies. Desertion, drunk and disorderly, and murder are only a few of the charges that Mobuto's squad carries-and keeping them in line might prove to be just as difficult as surviving the zealous, entrenched Covenant warriors who believe they have found the gateway to paradise. But as war rages across the ring's landscape for control of the installation's weapons and secrets, a far more terrible threat from deep within Halo's underworld is hellishly unleashed that transforms this conflict into a desperate battle of survival for UNSC and Covenant alike...