Maskull, a man longing for adventures, accepts an invitation from Krag, an acquaintance of his friend Nightspore, to travel to Tormance after a seance. The three set off in a crystal ship from an abandoned observatory in Scotland but Maskull awakens to find himself alone on Tormance. In every land he passes through he usually meets only one or two persons; these meetings often (though not always) end in the death of those he meets, either at his own hand or by that of another. He learns of his own impending death, meets Krag again, and dies shortly after learning that he is in fact Nightspore himself. The book concludes with a final revelation from Krag (who claims to be known on Earth as "Pain") to Nightspore about the origin of the Universe. The author turns out to support a variation of the doctrine of the Demiurge, somewhat similar to that propounded by some Gnostics.