This is book two in the Merchant Princes series. It would make considerably less sense without having first read The Family Trade. It also ends somewhat distressingly in the middle of things.
This is fast paced, full of action, and fun, with some interesting speculation, but he did mean things to some characters that diminished my enjoyment. The world remains well constructed and consistent and continues to depend on only a single McGuffin which carries over from the first book. Said McGuffin is fleshed out a little bit, but consistently and fairly. I was on a panel at Capricon this past weekend where it was discussed that people in a different society should actually think and act differently, and it occurred to me that at least in some important ways, Stross is doing this. The story arc is driven by people who are acting in ways that don't seem very reasonable to me, but they are consistent with the way people in those societies act.
7 out of 10.
**** PLOT HIGHLIGHTS -- SPOILERS ****
I can't remember everything for a linear summary.
Miriam spends most of the book in World 3 (the world that the renegade faction's amulets reach from the Clan's home) setting up her business model of patenting technology from our world. She's there both to stay hidden from the intrigue in Clan-home and to try to draw out the renegades. She succeeds and catches one of them, just a kid, and intimidates enough information out of him to confirm her theories. The founder of the renegade family lost his amulet, and when he reconstructed it from memory, he got the pattern wrong, so it accessed World 3 instead of World 2 (ours). But he was so far out west and knew so little of World 2 that he couldn't tell the difference, so he and his descendants were convinced that he'd been deliberately abandoned, motivating the generational feud. The hidden family the fomented the civil war that decimated the Clan 30 years ago.
Miriam also learns that Iris, her adoptive mother, is actually her real mother, who fled to World 2 to escape assassins from the hidden family and just stayed here in hiding because she didn't like the Clan very much and didn't feel safe there. She assures Miriam that she'd meant to tell her earlier, but Miriam dived into the whole worldwalking business too quickly and things were moving too fast. Miriam spends most of the book mostly avoiding Roland; she's not sure she can really trust him. At the end of the book, when she's decided that she's really in love with him, things go all pear-shaped. Miriam has Angbard arrange an extraordinary Clan meeting where she means to reveal her business plan, explain the hidden family, reveal that Matthias is a traitor, and get herself put in charge of managing the conflict in World 3. She means to use the captured kid as a messenger, while all of the Clan people would execute him out of hand as soon as they think they've tortured all they can out of him. Unfortunately, Matthias reads her mail and betrays the Clan to escape. He tips off our Feds about where the Clan's transport facility in Boston is; to them it's the source of a huge flood of drugs in the local market. And he orders all of the Clan personnel out of the World 1 side of the facility. Roland could cut and run, but he'd be leaving several Outer Families folks to the feds alone. So Roland rushes to New York/Niejwein, interrupting Miriam's meeting to get a rescue party together. The rescue party succeeds in clearing the building before the Feds can take it or Matthias' booby trap can go off, but Roland is killed. We're left not knowing quite where either Miriam or the Clan are going, though it seems like the Clan is probably going to follow Miriam's ideas since their own business model has been blown up.