For more than 200 years, the armies of the Emperor of Mankind fought to reconquer the galaxy - led by the superhuman primarchs, the Space Marine Legions brought countless worlds back under the rule of ancient Terra.

Now Horus, once honoured Warmaster and favoured son of the Emperor, has been corrupted by the whispered promises of Chaos. At his command the Imperium is torn apart by a terrible and bloody civil war, the likes of which the galaxy has never seen....

As Horus' rebellion gains momentum, more and more worlds flock to his banner. For some, it is through fear of annihilation; for others, it is out of malicious desire. Any that consider resistance are given one chance to swear fealty. To do anything other is to court disaster and worse.

Accazzar-Beta is one such defier, but in bringing this heavily fortified Mechanicum world to heel, just how far is the Warmaster willing to go and what truly is the meaning of a dark compliance? As two fleets engage across the gulf of the void, Accazzar-Beta will find out.