In Message in a Haunted Mansion, Nancy has flown to San Francisco to help out an old family friend who is turning a beautiful but dilapidated Victorian house into a bed-and-breakfast establishment. Nancy gets set to help with the renovation and is told about the strange goings-on and accidents. Always eager to solve a mystery, Nancy is determined to uncover the cause of the "accidents" plaguing the renovation of the old mansion.

Based on the third installment in the popular mystery series.