The Flight of the Eisenstein

Captain Nathanial Garro is a loyal follower of the Emperor and leader of the 7th Company of the Death Guard Space Marines. When Warmaster Horus' treachery is revealed on Istvaan III, Garro takes control of a ship called the Eisenstein and sets of to warn the Emperor about what he has witnessed.
James Swallow tells this story with gusto in The Flight of the Eisenstein, which introduces us to Garro and shows us aspects of his character that lead him to wanting to warn the Emperor about the treachery of Horus, and the threat that Horus is to the Imperium. While the Eisenstein is fleeing from orbit around Istvaan III it is fired on and sustains dangerous amounts of damage, despite this it jumps into the warp where the Chaos Gods begin to play with the ship. Garro and his men must survive if they are going to warn the Emperor, but the longer they stay in the warp the less likely it is that they will be able to.
Swallow does a good job of raising the tension and putting Garro through the wringer. If Garro succeeds maybe the Imperium can defeat Horus, but if the Eisenstein is lost in the warp Horus will most likely win. A good entry in the Horus Heresy series that focuses on the Space Marines themselves rather than the Primarchs for a change.

Blood Angels

The Blood Angels are just one of the many Space Marine chapters that defend humanity. They also carry a dark secret that they hide from the Imperium. When their Primarch Sanguinius died defending the Emperor from Horus this event leaves a psychic scar on the Blood Angels gene-seed, which is used to create the Space Marines. This psychic scar leaves the Blood Angels prone to reliving this traumatic event, which in turn makes them go mad with rage.
James Swallow in Deus Encarmine and Deus Sanguinius has told the story of these tragic fighters. On the remote cemetery planet of Cybele a group of Blood Angels clash with traitor marines from the Word Bearers. But things are not as straight forward as it first seems, as there are plots within plots as the Chaos forces have their own agenda for engaging the Blood Angels.
Within the Blood Angels events are also happening that threaten to split the whole Chapter. Battle-Brother Arkio performs heroic acts in battle that have his comrades talking about him being blessed by Sanguinius. Arkio's older sibling Rafen believes that something is amiss. This feeling is shared by experienced Battle-Sergeant Koris. Amongst this turmoil the trusted friend of the Blood Angels Inquisitor Stele of the Ordo Hereticus is playing his own game which may or may not relate to what is happening to Arkio.
this series has a slow build up but once it got going it was hard to put down.