When strange accidents start occurring at the local pioneer village, Nancy, Bess, and George go undercover to determine if the village is really haunted by the Lantern Lady, or if the accidents have a more deadly cause.
Nancy, helping out with a "chemystery" camp, a special forensics program for high school students, finds herself with a real mystery to solve when the professor who runs the camp suddenly falls into an unexplained coma.
Nancy receives a letter meant for a British heiress who has the same name and, in her attempts to contact the other young woman, faces danger from a man who operates a Lonely Hearts Club mail fraud.
Nancy, Bess and George witness the explosion and burning of a country mansion and help to rescue the occupants. They must then discover whether the fire was an accident or arson.
