Fly Trap (Twilight Robbery in the UK; personally I prefer the latter title) is the sequel to Hardinge's debut Fly By Night. It sees Mosca, her evil-minded pet goose Saracen, and smooth-talking, perpetually broke Eponymous Clent end up in the town of Toll, a town riven by superstition and mistrust, where those born under Beloved (read: petty gods) who are considered to be allied to the night are forced to come out only at night, living lives of poverty and desperation, while those lucky enough to be born under day-Beloved and be given day-names stroll around an artificially sunny town eating chocolate and drinking tea. Pretty much.
It's a highly contrived set-up when compared to the anarchic buzz of Mandelion in Fly By Night, and the book loses a star for that. Toll just doesn't feel as urgently alive, or as symbolically important, as Mandelion does; and while in Fly By Night Mosca and Eponymous' adventures felt tied up with the fate of nations, affecting the politics of a small and puffed-up town with a population of several hundred rather than several thousand just doesn't seem quite as important.
But Fly Trap is still another lovely book: twisty, delightfully steampunk, involved and joyful. "Not as good as Fly By Night" still equates to "better than lots and lots of YA".