Zelia, Talen and Mekki arrive at Aparitus, a planet of huge industrial machines and the cybernetic race called the Mechanicus. Now under the protection of the mysterious Inquisitor Jeremias, they still search for a way to reach Zelia's mother, but all is not what it seems on the forge world. A strange plague begins to spread, infecting technology and unleashing a host of gribbly monsters – the Nurglings!