On the war-torn world of Croatoas, the armies of the Astra Militarum do battle with the twisted servants of the Ruinous Powers. Against the backdrop of this increasingly desperate conflict, tanker Hadeya Etsul finds herself consolidated into a Cadian regiment, and placed in command of the Leman Russ Demolisher Steel Tread. Haunted by nightmares, surrounded by a dysfunctional crew, and striving to find her place amidst a proud and insular regiment with a culture so different from her own, Etsul must guide her crew to victory. But, as her regiment rolls out beneath the poisonous light of the Great Rift to join a death-or-glory offensive, the crew of Steel Tread are about to face the fight of their lives. If they cannot learn to work as one, how can they hope to survive?