Mandie and Celia travel with Mrs. Taft to visit Senator Morton in his hometown of St. Augustine, Florida, which is the oldest city in the United States. Among the senator's many servants is a man named Juan, who can't hear or speak. Mandie feels there is something sinister about the man, and his mysterious ways give her and Celia plenty of reasons to be concerned.

Why is someone sneaking into the girls' wardrobe and rearranging their clothes? Did Mandie and Celia really see the strange woman, Miss Lucretia Wham, from the top of the lighthouse on Anastasia Island? And why do even grown-ups in St. Augustine believe in ghosts?

Who's really behind all the mysteries taking place in St. Augustine?