Dead Reckoning.

Jett is a girl disguised as a boy, living as a gambler in the old West as she searches for her long-lost brother. Honoria Gibbons is a smart, self-sufficient young woman who also happens to be a fabulous inventor. Both young women travel the prairie alone - until they are brought together by a zombie invasion! As Jett and Honoria investigate, they soon learn that these zombies aren't rising from the dead of their own accord . but who would want an undead army? And why? This gunslinging, hair-raising, zombie western mashup is perfect for fans of Cowboys vs. Aliens and Pride & Prejudice & Zombies.