Good points re: name overload.
Spoilers ahoy, though I think if you're interested it won't make the book less appealing--oh, and a note. I didn't include this in the blurb but was going to in the final: this is a four-author collaboration. We created the world together and each wrote separate novels in it. They're each standalone, but myself I think they're more fun read in sequence. This is the final book chronologically.
Adewole is a professor of cultural anthropology and a brilliant linguist with deep knowledge of several languages old and new (think Daniel from Stargate). He is grieving the recent death of his much younger sister, who he was raising alone and who was more a daughter than a sister. He loses his tenure at his home university, the most prestigious in the world--as any academic can tell you a cause for grief of its own.
At Eisenstadt, Adewole is low on the totem pole; it's the center of the world's engineering knowledge, and its Dean doesn't like the humanities in general and Adewole in particular. When the inventor, an older woman, reaches the island in her autogyro (the subject of the first book), the government prudently decides that if anyone's going to control an island floating over their heads it's going to be them.
Adewole is sure he'll be left out of the survey mission and consoles himself that his best friend, an engineering professor, is going. The friend convinces the government Adewole is the only one who can translate, and he is brought along.
Up top, they find a backward, impoverished people who are nonetheless cheerful and resourceful. Adewole discovers a library of ancient books the inhabitants can no longer read--but he can. Among them he finds a handwritten notebook describing the making of a Machine God, a fusion of magic and metal. The islanders take an oath at 13 never to use magic and metal together, a belief so powerful it takes a lot of persuading to get them to talk about it at all; when he finally gets someone to tell him about it, Adewole learns it's for fear of the god who threw the island into the air and tried to kill them, a god the islanders' ancestors then killed but who they fear would be resurrected were they to use magic and metal together.
Adewole realizes he's on to something, tracks down where the Machine God's "heart" is buried, and finds it contains a hideously murdered little girl's spirit, a child who's been asleep or alone in the dark for a thousand years of pain. Her name is Alleine. She is the Machine God, and she accidentally threw the island into the air in hopes of getting away from the machine's energy source. Her body was disassembled ("killed") and its indestructible parts scattered over the island. The God's power is finite only in that it cannot create life or make something into something else--no lead into gold, for example--but otherwise, anything is possible. Alleine not only threw a city of 100,000 people into the air, for example, she accidentally created the "plague" of talking birds both on the island and in Eisenstadt, a phenomenon spreading across the globe as birds migrate.
Adewole's best friend has been tracking his discovery for his own gain and betrays him, stealing Alleine, the manuscript and Adewole's translations, and leaving him for dead. He intends to "resurrect" and control the God to rule Eisenstadt and beyond. Adewole realizes the government wants the God as well; it's a powerful weapon, and there's nothing corrupt about a government wanting a weapon like that in its own hands rather than an enemy's.
So it's up to Adewole to rescue Alleine before his former friend can reconstruct the God's body--and before the terrified Alleine does something dangerous with the power the God's body will return to her.