Stranded near a ghost town during a family camping trip in New Mexico, thirteen-year-old Joanna and her younger sister, Sally Rachel, find unexpected danger when they meet a mysterious old man with a large white dog and visit the cabin with the whispering walls.Stranded near a ghost town during a family camping trip in New Mexico, thirteen-year-old Joanna and her younger sister, Sally Rachel, find unexpected danger when they meet a mysterious old man with a large white dog and visit the cabin with the whispering walls.

While uncovering a mystery involving smuggled artifacts at south Texas's Goliad State Park, Joanna befriends an unusual boy who recounts the history of the area.

When twelve-year-old Joanna and her family spend a month near Longhorn Caverns in the Texas hill country, they must contend with the Scarlet Skulls, a threatening gang obsessed with violent computer games.

While staying at a summer camp near Fort Davis, Texas, Joanna and her sister Sally Rachel become involved in mysterious activities both at the fort and a nearby observatory.

While visiting their grandparents' Texas farm, Joanna and Sally Rachel hunt for the legendary treasure of outlaw Sam Bass to save the farm from a greedy developer and find out about a modern kind of bandit (view table of contents)

When twelve-year-old Joanna, her younger sister, and their cousin Mark discover a haunted house in the woods, they set out to resolve the mysteries surrounding it

Arriving in Jefferson, Texas, in 1868, during the violent reconstruction period, eleven-year-old Rip uncovers secrets surrounding a tunnel formerly used by runaway slaves.