The beginning of the novel is told from many perspectives – ranging from the rich nobility to low-class civilians – and tells of the opening phases of the siege on Vervunhive. The mega-city's neighbouring hive, Ferrozoica, amasses an army and marches on their former rival with an unknown agenda. The Vervun Primary militia prepares to repel the invasion forces, but as Vervunhive's High Master refuses to believe that Ferrozoica has mobilised against them, they are not given permission to arm their defence batteries before the Zoicans fire the opening salvos. Much of Vervunhive is plunged into panic and thousands perish in the first few days, and aid from the Imperial Guard is called for.