An unwelcome visit from Nathan Gombet, a sinister miser, leaves Nancy shaken. The miser claims Carson Drew swindled him from land condemned for the railroad. At the old stone mansion of the elderly Turnbull twin sisters, Rosemary and Floretta, a series of strange thefts of personal property, and ghostly noises leave the women frightened. Nancy is invited to investigate. Her search for answers is hampered by her worry regarding Carson Drew’s unexplained absence; is his enemy involved? The brave girl must use her courage and powers of deduction to explore the hidden passageways found in both the Turnbull home, and a neighboring mansion owned by Mr. Gombet.