Volume 2 (or the second half of volume 1, depending on how you look at it) of Charlie’s ‘Merchant Princes’ series.
It continues the story of Miriam Beckstein and her recently-discovered alternative-universe family of ‘world-walkers’. In this one, Miriam discovers that (not surprisingly) there is more than one alternative Earth, and takes advantage of that fact.
Two things bother me about all this, though. One is that at no point, it seems, does she or anyone else do any investigation into the world-walking ability, or the designs of the talismans that make it work. Though I have reason to believe that that point gets addressed in a later book.
The other problem I have is just how capable Miriam is. She’s a can-do hero in the Heinlein — even in the Doc Smith — mold. Which is all very well, and all kudos to Charlie for making such a figure a woman, rather than the ubiquitous men created by those illustrious earlier writers. But those characters were never very believable, and we live in more sophisticated times now, do we not? So it’s hard to believe in someone relatively ordinary who finds themself in another universe, and who just copes. Indeed, not just copes, but prospers.
On the other hand, I’ve said elsewhere that we don’t read SF for the characters, but for the stories (and the ideas, of course). And this is a great story that I sat up late to finish. And you can’t argue with that.