In 1900, Mandie is searching her dead uncle's mansion for a missing will when she finds a secret tunnel and strangers who claim to be her relatives.

Mandie and her friends attempt to unravel the mystery which includes missing gold, a train wreck, and a gang of robbers disguised as "ghosts."

Mandie and her best friend return to the attic to investigate the mysterious old trunk and discover a set of old letters which include some important and exciting information.

Mandie studies an old treasure map that has mysterious markings. When she and her friends search for the treasure, they receive threats from an angry man.

When Mandie goes home for Christmas, she believes her mother and stepfather are keeping an important secret from her.

The school year is over and Mandie is coming home for the summer. Ever since Mandie's mothe told her she was going to have a baby, the thought of having to share her mother with a brother or sister has caused problems.

When Mandie and her party take Jonathan to his aunt in Paris, they encounter a dangerous trap and a disappearing stranger.

Mandie and her friends stay at a chalet in Switzerland where singing is heard late at night in unintelligible words. What's really going on?

Mandie and her friends have a new mystery to investigate when strange sounds come from a seemingly abandoned fishing boat.

Mandie, Celia, and Jonathan are visiting Europe and see a strange woman on ship. While visiting a linen mill in Belfast, Mandie saves a little girl trapped inside.

Strangers digging in the mountains, and the disappearance of Mandie's uncle and a Cherokee boy lead Mandie to a new mystery.

Mandie is thrilled at the chance to visit Swain County, North Carolina, where her friend Joe Woodard lives. It's also her father's home territory, so with Snowball leading the way, Mandie and Joe decide to explore the old log cabin where Mandie had lived with her father before his death.

Mandie must find her late father's missing will or risk losing ownership of his house.

When she and her grandmother return to Franklin, North Carolina, for a Christmas visit, thirteen-year-old Mandie worries about how all the guests will get along with each other and wonders about the appearance of a mysterious package addressed to her.

While on spring break from her girls' school in North Carolina in 1902, fourteen-year-old Mandie joins her college friend Joe in solving a mystery in the nearby mountains.

Mandie investigates some suspicious noises coming from a warehouse in a dark alley, noises that just might be connected with the theft of a precious heirloom from her grandmother's mansion.

While digging through a chest, Mandie and her friends discover wonderful old quilts, some of which were made by her Cherokee grandmother. Uncle Ned shows up with another quilt that has some writing on it. However, he tells Mandie to pack it away because the message it contains is dangerous. Curious Mandie can't resist finding out what that message is.

Mandie's favorite teacher, Miss Hope, has gone missing.