Staying in an old Victorian mansion while on a trip to San Francisco, Nancy investigates the "spirits" that are scaring people away.

When their parents divorce, twelve-year-old twins Felix and Maisie move with their mother to live in the attic of a historic Newport, Rhode Island, mansion where they discover a hidden room that carries with it an intriguing secret.

"When Felix gets a crush on his friend Lily, who was adopted from China as a baby, he decides to try to take her back in time to learn more about China. After being caught by Maisie, the twins find themselves transported to a small village on the Yangtze River, leaving Lily behind in the present. In China, the twins meet Pearl Buck in the days just before the Boxer Rebellion. With bandits chasing them, they flee to safety in Shanghai. The twins return...

After years in foster care, April gets to live in a mansion where she and four other children are caught up in a mystery related to a missing heir, a lost legacy, and the Phantom.

Charlie, Anna, and Emily must overcome their differences and work together to solve various puzzles leading to the secret treasure a famous female explorer left in Idlewood Manor before the adults do.

Mandie investigates when strange noises disturb the night at the Patton mansion in Charleston, South Carolina, and her jewelry, as well as her grandmother's, is stolen.

Winston attends a weekend of puzzles at a famous musician's mansion, but when he and other young guests pursue a thief, they find themselves in big trouble. Puzzles for the reader to solve are included throughout the text.

When their parents divorce, twelve-year-old twins Felix and Maisie move with their mother to live in the attic of a historic Newport, Rhode Island, mansion where they discover a hidden room that carries with it an intriguing secret.

Tori and her mother jump at the opportunity to inherit great-aunt Muriel's colonial manor by living without modern conveniences for two weeks, but Tori finds herself distracted by Caleb, a cute boy on staff.