Charles Stross’s The Hidden Family is the second book in a multi-volume series, The Merchant Princes. The dust jacket copy calls it a fantasy; this is a rather misleading description and may keep away some of the readers who would most appreciate the books. The story takes place in a low-tech world reached by sideways time travel; L. Sprague de Camp’s classic Lest Darkness Fall takes place in a low-tech setting reached by time travel into the past, and is universally regarded as science fiction. The process of travel is a “wild talent,” an old science fictional concept, inherited in strictly Mendelian fashion; and in any case the means of travel to a different world is simply a vehicle—what matters is what the author does with the world.

And the story in the other world is the hardest of hard science fiction, in an unusual sense: the science is economics. Stross’s protagonist encounters first one, and then a second alternate world where the Enlightenment never took place, and Adam Smith’s defense of free market economics is unknown. As a result, both are trying to get rich off of mercantilist policies. And as a proper science fiction heroine, Miriam Beckstein promptly sets about trying to engineer a change in the world, through the introduction of superior rational methods of doing business. There’s none of the customary fantasy admiration for the wisdom of the remote past in this story; Stross invites his readers to embrace change.

For libertarian readers, in particular, the specific economic ideas Stross presents will have a pleasant familiarity. This is a novel one of whose parts has the title “Capitalism for Beginners.” In fact, in an odd way, the book is a sibling to last year’s Prometheus winner, Stephenson’s The System of the World. Both books look at the desirability of Enlightenment values of scientific rationality, technological advance, market economics, sound currency, and equality under the law against societies that have barely begun to encounter them: in one case, the actual historical past; in the other, alternate presents where modernity was never conceived (in one case) or stillborn (in the other). I’m particularly happy to see a novel where the triumph of Bonnie Prince Charlie is shown, not as a glorious romantic dream, but as the catastrophe it really would have been, given the Stuart support for Tory reaction and hatred of Whig progressivism.

The Hidden Family was also enjoyable to read. It has an ingenious plot that resolves the first volume’s loose ends. It has a heroine with a lively mind and a strong will, accompanied by a cast of excellent supporting characters. It plays with many of the classic motifs of romance fiction but doesn’t surrender to them. Stross has given us entertainment, but a superior entertainment, one that fans of alternate history ought to give notice to, as well as libertarian readers in general.