When Harriet discovers that she has yet another lost aunt—a cowgirl named Formica—she jumps at the chance to join her two detective aunts on a visit. Aunt Formica's ranch is being plagued by devious cattle rustlers, and she needs Harriet's help to track down the bandits and save the ranch. But the Wild West carries dangers all its own … From bestselling novelist Alexander McCall Smith comes a charming new mystery that will keep young readers guessing—and laughing—from the first clue to the last.