When we last left Nadya, she'd lost her leg and her mentor, Mrs. T, to pirates who were kidnapping Skylungs, but it remained a mystery as to why.
Now the Orion cloudship lands in Far Agondy to deliver a baby leviathan to a wealthy client and Nadya finds a strange darkness hanging over the city and the Panpathia, the space between worlds that Skylungs like Nadya can travel.
She delivers the leviathan to Alan Salawag (a thinly-veiled reference to skaliwag, perhaps? hint hint wink wink), the Lord Secretary of the city, and makes new friends. Through them, she discovering kids like her are being kidnapped all over the city. Their benefactor and protector, the Gossner, generously offers to make Nadya a prosthesis.
Nadya and her new friends cleverly outwit the kidnappers, until one of her friends is captured and she must face the dreaded gang leader, Silvermask, to get him back. She also learns why Silvermask is kidnapping Skylungs like herself, and she fears for Mrs. T.
I won't spoil it and say how it ends, or what the plot twist is. Just know, you root for Nadya the whole way through, although the book never resolves Mrs. T's fate, setting it up nicely for a third story.