[1] A dirigible with a dead pilot has been passing over Victorian London in a decaying orbit for some years, arousing the interest of the Royal Society, as well as scientist-explorer Langdon St. Ives and the evangelist/counterfeiter Shiloh.

St. Ives and his friends of the Trismegistus Club are more concerned with the inheritance of Jack Owlesby, a fine young fellow affianced to Dorothy, the beautiful daughter of toymaker/inventor William Keeble, who builds jolly boxes for space aliens, oxygenators, and gigantic emeralds.

Jack's late father bequeathed him just such a gem, but also left behind dark knowledge developed in association with the evil Narbondo.

St. Ives and the heroic tobacconist Theophilus Godal suspect that Narbondo and his assistant, the pimply Willis Pule, are using this knowledge to raise the dead, possibly for nefarious purposes.

When poor Bill Kraken steals what everyone assumes to be Owlesby's emerald in a fit of alien-induced delirium tremens, the ambitions of Shiloh, Narbondo, Drake, and Pule collide with the heroism of St Ives and Godal and the scientific greed of Parsons of the Royal Academy as Hampstead Heath turns into a carnival of flying skulls, crumbling ghouls, crashing spaceships, and the sparking perversity of the dreadful Marseilles Pinkle.