Mona Moon travels to Merry Old England to visit Brynelleth, Robert Farley's ancestral home, for the first time. Hoping to make a good impression, Mona finds she is rebuffed at every turn by Robert's friends and even his servants. Events turn more sour as the staff quits after seeing ghosts, and a phantom keeps sabotaging repairs made to the manor. Despondent, Mona wants to return to the United States, but her trip is delayed when an American agent is discovered murdered at Brynelleth. She can't leave Robert in such a lurch and begs her good friend, Lady Alice Nithercott, to help her find the culprit, who seems to be out for blood—Mona's blood!