[Edited after reread, additional comments below]
This is the fourth of a six-part series of connected stories set in the same world, which can supposedly all be read as stand-alones. There are references to earlier events, and foreshadowing of the larger picture, but this does read quite well as an independent story, even though it is probably more sensible to read the books in sequence.
Many of the same characters reappear, of course, not just Hadrian and Royce, the likeable rogues now royal protectors, but also Arista, the feisty princess, Thrace the village girl turned puppet empress, Esrahaddon the thousand year old wizard, and a whole raft of others.
The plot concerns an intercepted message, which necessitates Royce and Hadrian becoming (rather bad) sailors and a great deal of - well, splicing the mainbrace and climbing the mizzen, or some such, with pirates and storms at sea and all the usual shenanigans. All good, exciting stuff.
We also get to see something of the southern coastal reaches of Elan, including the dwarvish tower of Druminor, built on a volcano, and the goblin homelands of Calis, all of which is far more interesting than the vaguely medieval world we've seen so far. The political plotting is still going on in the background, but it takes second place to the action, which is all to the good.
The whole series has been enjoyable to read, but this episode really sees the author reaching a new level. The plot is much tighter, with a neat twist at the end, the main characters acquire new depth and complexity, and there are far fewer quirks and anachronisms in the writing. There is less humour, perhaps, but that's inevitable as the story changes from amusing capers to defending the world. A good 4 stars.
[Edited after reread]
Not a lot to add to my original review. There were a lot of new characters added in this book, some we met briefly in previous books, and some entirely new, and occasionally I got confused. The Tenkin, Staul, is particularly poorly introduced, seemingly dropped in from nowhere as if we should know who's being talked about, but if he was mentioned earlier it was very oblique.
The three women, Arista, Thrace/Modina and Amilia, continue their painfully slow rise to competence, although they still needed rescuing at regular intervals. Arista, in particular, is a puzzle. Despite Esrahaddon declaring in the previous book that she is potentially the most powerful person in the world, and other characters talking about her intelligence, she displays a breathtaking level of idiotic decision-making. A bloke with a sword saves her from one horrible fate, but instead of learning from that, she ends up even worse off. Silly woman. Amilia gets temperamental about Arista, and Modina must have elf ancestry to account for her amazing eyesight, managing to recognise the disguised Arista from her fifth floor window. Clever, that.
The other half of the book, the adventures of Royce and Hadrian, is a cracking read, with lots of action, an introduction to the mysterious region of Calis and its scary inhabitants, and the wonderful dwarf-built tower of Drumindor (which I would love to see realised on the big screen actually - a set designer could have terrific fun with it). I gave it four stars last time, and I see no reason to change that. Originally read August 2011.