The fourth of the Spiral Arm series. It's not a work divided up into four chunks, but the weight of the series before does supply more to this work. Also, there will be spoilers ahead for the first three.
It opens with three, as the opening line observes. First there is Bridget, who summoned together such Hounds as her message could reach. She tells them she summoned them for her daughter, and then that this is because a Shadow of the Confederacy spirited her away. She carefully omits that this was probably voluntary on Mearana's part. But she gets allies to leave the League going after her.
And second, there is Mearana herself, traveling with Ravn Olafsdottr, to lure her mother after her, because her father is prisoner in the Confederacy, and her mother would not come for her. She learns more and more about the place, and the conflict among Shadows that resulted in her father's first kidnapping.
And third, there is Donovan, Gidula's prisoner. He learns how he came to survive, more about the struggle, and Gidula's principles of government. He knows Gidula wants him because of Padaborn's Rising, and the secret way out of the Secret City that saved him. He learns that many of Gidula's subordinates, even his magpies, are loyal to Padaborn -- and suspects that he wanted Donovan more troubled than he is, to dash their hopes. Gidula sets up a pasdarm, a mock combat, and Donavan guesses it to be a way to accidentally cripple him; he uses it instead to win over the man who was to do it.
And intrigues thicken from there, and conflict, thicken from there. After all the revelations of the first three, it's amazing how many more can spring, completely naturally, from the events of this and them, without even making the past look over-crowded with events. Donovan discovers many things about Terra's past.
It's a book that benefits from being read with care. I am quite sure that I didn't get all the allusions, even on a second reading, but such as I did helped flesh out this enormously and gorgeously elaborate world.