Charlie Harris and his wife, Helen Louise Brady, have arrived in Ireland for their three-week honeymoon. After a few days in Dublin, they head west to County Clare, ancestral home to Helen Louise's extended family, the O'Bradys. Her cousin, Lorcan O'Brady, is the current owner of Castle O'Brady, which he runs as a bed-and-breakfast with his wife Caoimhe and daughter and son-in-law, Bridget and Rory Kennedy. Upon arrival at the castle, the newlyweds are shocked to see a body falling from the roof. The dead man is centenarian Finn, Baron Brady, Lorcan's great-uncle. Lorcan becomes the new Baron Brady. But how did the late baron come to plummet to his death? Was someone in a hurry for Lorcan to assume the title and ownership of the estate? Or is there another reason for wanting Finn dead? Charlie and Helen Louise find themselves asking these questions and more as they realize the local garda won't be able to solve the crime alone - Charlie and Helen will have to investigate themselves. Meanwhile, Charlie's feline friend Diesel is home in Athena, Georgia, and encounters his own mystery, one unknown to his human hosts. The spirit of Charlie's grandmother lingers on in the attic of the old farmhouse, and Diesel plans to find out why.