In this fourth installment of a middle-grade adventure series, a teenager arrives in a Colorado city and encounters a string of challenges.

It’s 1898, and Ruby Oliver and her Pa move from rural Cripple Creek, Colorado, to citified Colorado Springs. Pa is a simple, loving man but has trouble expressing his feelings. Ruby’s milliner stepmom is gentle and sympathetic to the moody teen, who’s blossoming into an inquisitive and independent young woman. She tells Ruby that age 13 is full of “ups and downs,” and the teen quickly discovers this. Pa taught Ruby about the great outdoors and took care of “all her schoolin’ ” in their rustic log cabin close to the mountains. Now, it’s summer vacation, and Ruby is sorely in need of a diversion. Her homespun but crafty Pa orders her to “stop shilly-shallying and find something to do,” so they purchase a buggy. With her two pet donkeys, Maude and Willy, Ruby enters the livery business. This gives her freedom of movement and expands her horizons as well as exposing her to the comings and goings of the townsfolk and strangers. (Pa works hard, giving Ruby plenty of time to roam unsupervised.) Roy O’Rourke, a teen from Cripple Creek, has run away to Colorado Springs to escape an abusive father and moves in with his Aunt Agnes, an odd bird who awakens Ruby’s unsettled interest. Roy encounters Ruby, becomes her partner, and the story begins to gallop. A crime wave hits Colorado Springs when the Bat Bandits (they wear black capes) swoop into town. Ruby’s ears prick up and she begins to add things up. Mixed into the plot just a bit is the novel Dracula. Ruby reads the book, and it makes her a little uneasy and incites her imagination. A former teacher, Oswald skillfully uses the horror classic to enhance the plot and mood and to perhaps arouse young readers’ curiosity about literary technique without detracting from the action. The story moves quickly (readers will have to hold the reins tightly) as the crime-solving duo chases leads. The humor is plentiful and folksy, and Ruby and Roy make a great team. Hopefully, they’ll be together again soon.

Two young sleuths solve a mystery in this witty, swiftly paced tale.