Sherlock Holmes has been missing and presumed dead for some time, and his grief stricken landlady, Mrs Hudson, is anxious for a distraction. However, she is in for a culture shock when she travels to Ireland with her friend Kitty Melrose, to try and stop a forced marriage. What she finds is a countryside steeped in superstition and beliefs in the old ways, a place of fairy forts and holy wells, of changelings and banshees. A place moreover where an impoverished peasantry remains under the heel of oppressive English landlords, but not for much longer. Times at last are changing. A brutal murder followed by the arrest of someone Mrs Hudson is determined to prove innocent, leads her into mortal danger. At the same time, she is amused to find herself courted by an elderly widower with a roving eye…