Five orphans – Victor, Amelia, Vanity, Colin, and Quentin (see Names and identities below) – who have spent their lives in a luxurious but strict and secretive British boarding school (Saint Dymphna's School and College for Destitute Children), begin to discover that they are different from the other children that they so rarely see.

The story largely concerns the main characters' investigations and discoveries about an otherworldly power struggle, and their place within it.

("Secunda," the narrator of the novels, chooses a name that expresses her admiration for Amelia Earhart and her fascination with exploration, geography, and travel.)

Reginald Boggin, the headmaster of the children's school, is actually Boreas, the ancient Greek personification of the north wind.

Wright structures his fictional world on the Greeks' primal creation myth, the rebellion of the Olympian gods against their progenitors, Saturn and the other Titans.

In his cosmos, the Phaiacians are not merely the ancient people familiar from the Odyssey, but a race of otherworldly beings with remarkable abilities.

Wright is to some degree comparable to Rudy Rucker as a science fiction writer who has devoted significant attention to the theme of the fourth dimension.