Red in Tooth and Claw by Lish McBride

Faolan Kelly’s grandfather is dead. She’s alone in the world and suddenly homeless, all because the local powers that be don’t think a young man of sixteen is mature enough to take over his grandfather’s homestead…and that’s with them thinking Faolan is a young man. If she revealed that her grandfather had been disguising her for years, they would marry her off at the first opportunity.
The mayor finds a solution that serves everyone but Faolan: He hires a gunslinger to ship her off to the Settlement, a remote fort where social outcasts live under the leadership of His Benevolence Gideon Dillard. It’s a place rife with mystery, kept afloat by suspicious wealth. Dillard’s absolute command over his staff just doesn’t seem right. And neither do the strange noises that keep Faolan up at night.

When Faolan finds the body of a Settlement boarder, mangled by something that can’t possibly be human, it’s clear something vicious is stalking the palisades. And as Settlement boarders continue to drop like flies, Faolan knows she must escape to evade the creature’s wrath.