Zea’s first visit to an alien world lands her on dark and desolate Purgator, an interstellar trade hub and prison. Twin moons of ice and fire, Zzard and Ffurno, are home to winged opposites of cold angels and hot demons. An indentured criminal named Bro’sys saves Zea’s life. Zea agrees to help Bro’sys rescue his sister, Sys’bro, from prison. Zea faces Wro for the first time, and convinces her to escape. The four strangers battle their way to the surface. Zea throws herself upon the court of the Arbiter to seek mercy for Wro. Zea discovers for the first time the cruel apathy of cosmic legislation. The arrival of the Spikelings sows war between Zzard and Ffurno. The eruption of their conflict disrupts the court of Purgator, freeing Wro, and leading Zea, Bro’sys, and Sys’bro on a scramble for the Vault.