 Diana Winthrop and her mother arrive in Paris, where a World Exposition is taking place. Mrs. Winthrop had started to feel very tired during the journey, so after they check into their hotel, Diana calls for a doctor. After examining Mrs. Winthrop, the doctor sends Diana in his carriage to his own home, where his wife prepares a medication. A number of things seem odd to Diana, but things become much more worrisome when she returns to the hotel. The desk clerk does not remember her, her signature has disappeared from the hotel register, someone else is occupying her room, and her mother has completely disappeared.