Greek underworld are the unburied which can't be taken across from bank to bank until they receive a proper burial. Across the river, guarding the gates of the underworld is Cerberus. There is also an area where the Judges of the underworld decide where to send the souls of the person — to Elysium, the Fields of Asphodel, or Tartarus. While Tartarus is not considered to be directly a part of the underworld, it is described as being as far beneath the underworld as the earth is beneath the sky. It is so dark that the "night is poured around it in
In the Courts of the Crimson Kings will proceed to the next stage. Though both are unsure what this means, but they soon discover that three interplanetary "Gates" have opened up on Earth, Venus and Mars, each leading to another world. The book ends with Teyud and Jeremy visiting "Vow'da" (Moon-World) the new world on the other side of the Martian gate. "Publishers Weekly" called it "charming", and praised Stirling for "successfully creat[ing] a truly alien environment", but criticized his "inclusion of pirates with eye patches, heavily armored guards riding 'fat-tired, self-propelled unicycles' and other moments of near-parody." "Kirkus Reviews" lauded Stirling's "magnificently wacky Martian biological machines"