Book #5 in the Merchant Princes series, sequel to The Merchants’ War.
The U.S. Government have become really pissed off with the world-walking Clan, and send a small nuke into the Gruinmarkt. It misses the clan but takes care of the new king who was waging war on them. Miriam is pregnant with a royal child and manages to parlay that into being crowned queen-widow. The conservative faction in the Clan view the nuke as a deadly insult and want revenge.
This is another heady mixture of feudal intrigue, U.S. spycraft, politics and economics. Stross is very good at taking ideas and extrapolating them in interesting ways. Most of the Clan were only slightly more forward-thinking than the rest of their feudal world. Miriam’s arrival and the discovery of new worlds they can walk to has overturned many long-held assumptions about their unique way of life. Matters are coming to a boil and will be resolved in the sixth book of the series.