It is the 30th millennium. Humanity is caught in the midst of a fratricidal war between those of the meta-human Space Marines who are loyal to the Emperor, and those who no longer are.
The once noble warriors of the XII and XVII legions are cutting a bloody path throughout the realm of Ultramar, committing boundless atrocities out of sheer spite and hatred for their cousins belonging to the XIII legion.
In this episode we gain a glimpse of the aftermath of the battle on planet Sathus, and the living nightmare taking place on a starship manned by traitorous legionaries, as they bide their time on the approach to planet Calth.