Horus Heresy: The Buried Dagger (English)

Dark clouds gather over Terra as the final battle for the throne approaches... The treacherous primarchs rally around the Warmaster's banner, and Mortarion is sent ahead as the vanguard for the traitorous forces.
But as they draw near, they become lost in the Warp and are struck by a horrifying disease. Though they are considered unbreakable, the legendary Death Guards are now brought to their knees. To save his legion, Mortarion must make a terrible pact that will condemn his sons for all eternity!
Meanwhile, in Terra's monasteries, plans are set in motion to create rebellion and chaos ahead of Horus's armies. Malcador the Sigilite takes matters into his own hands in his attempt to quash any uprising. But he uncovers a conspiracy that will require all his cunning and skills to overcome.

Author: James Swallow