Charles Stross is every inch a science fiction writer. So much so, in fact, that even when he’s writing fantasy it feels like he’s writing science fiction. In this second installment of the “Merchant Princes” saga, he continues to entwine serious speculation about economic systems with his ongoing fantasy thriller plot.

“The Hidden Family” is really the second half of “The Family Trade,” broken up for publishing purposes. However, that’s not to say that it concludes a self-contained episode of a greater series. Its ending is still open-ended, with only a few plot points wrapped up. Our heroine, Miriam, has discovered her ability to walk between worlds. In the first book it was revealed that she was a long-lost relative of a crime syndicate that posses this world-walking ability, and uses it to enrich themselves in two universes: ours, where they courier hard currency, and a medieval one where they ferry drugs. It’s a very efficient system, but Miriam finds it pathetically short-sighted and limited.

In the last book she gained access to a third universe, this one closer to our industrial revolution. In it the American lands are still under a repressive monarchy, and France is a bitter rival. As she knows that the Family doesn’t have access to this universe, she starts to set up her business model there, importing patent ideas and setting up a workshop. In this way she plans to enrich herself and advance the economy of the new world. She explains the wealth-creating benefits of capitalism in page-long lectures to her allies that come from the medieval universe.

Various family factions are still out to get her in all the universes, and she’s still not sure who she can trust. She’s trying to protect her adoptive mother from getting entangled, as well as her friend Pauline who is helping her set up her various ventures. She has to convince the Family that she’s no threat to them, but that she’s one of them, and that her way of doing things is superior. This is no small task, but she’s pretty much up to it. In that grand science fictional tradition, she’s as competent and unflappable as they come. She’s a journalist that was covering the tech boom around the year 2000, plus she’s got a background in medicine, so any technical, industrial, forensic, investigative challenge and she’s got it covered. That would leave legal matters uncovered, but luckily she’s got Pauline, who’s a paralegal. Thank goodness for that, we wouldn’t want Miriam to be unrealistically talented or anything.

One gets the feeling that if Stross could have, he’d have written this as a science fiction book. But even with the multi-verse theory of quantum mechanics, there’s no honestly science fictional way to limit commerce between those universes, once contact is established, to only a few people being able to cross over, and to have that ability be genetically limited. So instead it’s a fantasy, but not one that would be recognizable as such to your average Tolkein reader. All its mixed-up genre tropes aside, this is a fun and intelligent read, and it will be very interesting to see where Stross ends up going with it.