Faced with an ork invasion of Piscina IV, the 3rd Company of the Dark Angels believes the threat to be minimal. As enemy numbers continue to increase, their commander, Captain Belial, insists that his Company are strong enough to resist. But Scout-Sergeant Naaman knows just how dangerous this foe can be, and when a renewed greenskin offensive takes the Dark Angels by surprise, the orks swarm towards Kadillus Harbour. Little do the Dark Angels know of the technological power available to the xenos, and the true scale of the threat they face. Belial, Naaman and their fellow Astartes fight a desperate siege at Kadillus, knowing that they must hold out until Imperial reinforcements arrive or the planet will be lost.