When someone commits robbery and murder aboard the luxurious train on which Myrtle Hardcastle, her Aunt Helena, her governess Miss Judson, and cat Peony are traveling, Myrtle is determined to find the culprit.
When twelve-year-old aspiring detective Myrtle Hardcastle learns her neighor in quiet Swinburne, England, a breeder of rare flowers, has died she is certain it was murder and that she must find the killer.
Twelve-year-old Young Lady of Quality and Victorian amateur detective Myrtle Hardcastle returns, and now she is on the trail of a serial killer in her hometown of Swinburne.