One year after the events of the previous novel, Valkyrie Cain is working with Skulduggery Pleasant to capture villains on the behalf of the Sanctuary.
When Baron Vengeous is broken out of prison by another villain, Billy-Ray Sanguine, he begins searching for the armour of Lord Vile. The armour will help him resurrect the Grotesquery, a monster with the power to bring back the evil gods known as the Faceless Ones.
Valkyrie and Skulduggery ask an informant about the location of the Grotesquery, who says he will only help them if Skulduggery kills Valkyrie. Skulduggery tricks him by shooting an illusion of her instead. The pair go to the Grotesquery's hiding place and find that The Baron has already taken it.
Valkyrie is kidnapped and taken to a church to the Faceless Ones, where The Baron attempts uses her blood and the power of Lord Vile's armour to revive the Grotesquery. Skulduggery rescues Valkyrie and steals the Grotesquery, which he hands over to the Sanctuary's scientists. However, the Grotesquery has already begun to revive, and escapes after a fight with Skulduggery, Valkyrie, and Tanith Low.
Skulduggery suspects The Baron is a pawn in someone else's plan, and accuses the Sanctuary's Grand Mage, who expels Skulduggery from the Sanctuary. At a family reunion, Valkyrie is attacked by a vampire working for The Baron, but she escapes.
Skulduggery, Valkyrie, and Tanith battle and defeat The Baron and the Grotesquery. Before dying, the monster screams to summon the Faceless Ones.
Later, Sanguine meets with his secret master, who is happy that the Faceless Ones have been summoned and is preparing to unleash them upon the world. The story ends with Valkyrie and Skulduggery wondering about the true identity of The Baron and Sanguine's master.