The Serpent Sea is book 2 of Martha Well's series featuring the Raksura, who are shapeshifters, some of whom look like dragons in their non-human form - it's the follow-up to The Cloud Roads, which I reviewed here a few weeks back.
In that book, our main character (whose name is Moon) discovered that he was one of the Raksura, as he had been living on his own since childhood and hiding the fact he could change into a non-humanoid form. I say 'non-humanoid' but in this universe, there are no humans as we know them, but there isn't really any other term we can use. Anyway, in The Cloud Roads, Moon came to be part of a group of Raksura and spent a significant chunk of that book dealing with the fact he wasn't alone any more and also dealing with the dynamics of that group and a culture with which he had no familiarity. And there was also a Big Bad, in the shape (sorry!) of another group of shapeshifters called the Fell, who are just destructive and who had targetted the group of Raksura that Moon had joined.
In The Serpent Sea, we are dealing the immediate aftermath of that book's events, as the Raksura are forced to look for another home and do so by trying to return to the huge tree where they used to live centuries before. However, when they get there, they find that the tree itself is dying because a vital part of it has been stolen and the rest of the book is dedicated to trying to find and reclaim that missing part. Alongside that, Moon is still trying to negotiate his place among the Raksura, more than aware that he is committing social blunders on a regular basis - Raksura who are like him are traditionally sheltered and cosseted and Moon's upbringing and past experience means that he is anything but.
It's a good book, if not quite as good as The Cloud Roads, and I'm struggling to put my finger on why that is. All the elements I enjoyed about the first book remain - the worldbuilding is fantastic (with a large section of the book set in a city built on the back of a giant sea monster, for example), the characterisation is strong and the writing draws you on. But The Serpent Sea just doesn't quite work as well for me, maybe because Moon is on his own among groundlings for a large part of the book and that doesn't interest me as much as the dynamics among the Raksura.
Anyway, regardless of that it's still a good book and I look forward to reading more from this author, particularly within this universe - the next book in the series is The Siren Depths, and there are also some books of shorter stories in the same setting.