I think this is the first time I've been genuinely burned by unknowingly picking up the first in a proposed series of books (and I say proposed, because I can find absolutely no mention on the internet that a sequel is even being considered.) While it does provide a solution to the most immediate part of the plot, so much is left open-ended, it broke my heart. So it lost a star to that, unfortunately.
Other than that, the book offers a fast read (though it does suspiciously drag in its first third, despite being pretty short) and engaging characters that are just left of being cartoonish, but in an entertaining way. And Jett and Gibbons definitely offer something different by way of heroines, in westerns or any other genre for that matter, coming from two different directions: Jett dresses like a boy to avoid harassment as she makes her way through the Old West in an attempt to find her brother, her only surviving family member after the Civil War, while Gibbons is an inventor, indulged by her rich and eccentric father, enlightened and liberated, with all of her faith put in Science. The two clash, the two become best friends. White Fox, the main male character, is sweet, but sort of inconsequential, and while there's a sulfurous whiff of brimstone and love triangle about their relationships, the book itself is obviously more interested in developing Jett and Gibbons' friendship.
Extremely historically accurate (as steampunk strangely seems to be) with a sense of fun and a wink to the plot on behalf of the authors, and just a bit of horror, I would be looking forward to learning what the airship means, if the man Shepherd was communicating is behind the disappearances, what the spell book White Fox received from his friend has to do with anything if the authors seemed to have any intention of continuing the story. Please, ladies? I'd definitely keep reading!