This is book 10 in the Chronicles of Elantra. Kaylin Neya is living at the Imperial Palace with Bellusdeo since their apartment got all blowed up by the Arcanists. Neither is happy there. Over the course of the book, Kaylin and a variety of other people explore possible new places for Kaylin and Bellusdeo to live. Antics ensue.
Kaylin is recently returned from a visit to the West March with Teela, Severn and Nightshade/Calarnenne. They brought back some of Teela's lost compatriots from a previous, much more tragic visit to the regalia and it turns out those compatriots have sort of ... changed. Kaylin brings Bellusdeo and once of the old buddies on patrol and they stop in at Evanton's, where Mandoran (you know, I would not be surprised if I spelled one or more of these names wrong) manages to piss off elemental water. Then, it turns out that Annarion, who is visiting older brother Nightshade in Nightshade, has sort of woken up that tower a lot more than Nightshade ever intended to. So Kaylin gets soaked a couple of times, first calming the water down and then using the water route out of Nightshade after rescuing Annarion.
Alas, that isn't the end of trouble out of Nightshade. Those Barrani looking scary guys from many books back? They get out and start stomping around making trouble. One heads over to the High Halls intending to suck all the names out of the lake (HEY I DID MENTION SPOILERS HERE DO NOT COMPLAIN NOW) and the other one heads over to Helen.
Evanton gave Kaylin an address in a Really Nice Part of Town as a possible place to live when earlier efforts to find an apartment that Kaylin could afford and would satisfy Emperor criteria for keeping Bellusdeo safe had comically failed. The address turns out to be a sort-of Tower that is improbably named Helen. Nice place, very welcoming, however, the Ancestor attacking has to be dealt with first, and in the usual way: runes come to life on Kaylin and she has to put them in the right spot, and then she has to figure out why _that_ didn't work. Inevitably, singing is involved.
With Helen squared away, it's time for an epic battle in which the Dragons and the Barrani and the Swords and the Hawks and Kaylin's motley crue all fight the other Ancestor. While name-based communication is crucial to all aspects of this novel, the relationship between Ynpharion and Kaylin is probably the best developed of all of them and quite amusing.
By the end of the book, Kaylin has a suitable place to rest her weary head, and plenty of space for all her friends to move in with her, or at least crash when they don't feel like going home/home isn't very safe for them. And there are all these basements with research in them to explore; maybe one of them will help us figure out what to do about Ravellon . . .
I'll keep reading. Don't start here.