When Harriet Bean's father mentions that he has five sisters―whom Harriet has never met―she is immediately intrigued. Harriet is determined to uncover the whereabouts of her five lost aunts, but with nothing more than an unfinished family portrait and a few outdated clues, will she be able to locate them? Join Harriet in her search to reunite her father with his five lost sisters―Veronica, Harmonica, Majolica, Japonica, and Thessalonika.

Harriet Bean loves nothing more than a good mystery. And together with her five extraordinary aunts (Veronica, Harmonica, Majolica, and twins Japonica and Thessalonika), she is always ready to take on a new case. Harriet doesn't think twice when her mind-reading detective aunts Japonica and Thessalonika enlist her help in catching a cheat at the racetrack. After all, Harriet is just the right size to go undercover as a jockey. But when the plan takes an unexpected turn, Harriet finds herself in the saddle!

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.