Warhammer 40,000

The garrison world of Callistra Mundi is threatened by traitor forces — none other than the insidious Alpha Legion. Like so many before it, this attack will not come as a traditional legionary assault, but as a Harrowing. Operatives and turncoats are revealed within the Mechanicum ark freighter Omnissiax and her attendant battlegroup, and confusion will reign amongst the loyalist defenders. And only when none can tell friend from foe will the true destruction begin...