Mysteries in our national parks

Twelve-year-old Jack, his younger sister, and the family's teenage foster child Troy go to Yellowstone National Park, where Jack's mother, a wildlife veterinarian, is investigating the report that wolves reintroduced to the park have killed a dog there.

Twelve-year-old Jack and his younger sister visit Mesa Verde National Park, where they delve into the park's history while gradually uncovering the mysterious past of their family's teenage foster child Lucky.

Grizzly cubs are disappearing from Glacier National Park, and the Landon family must figure out why! But for Jack, the real mystery is his sister Ashley's strange behavior. What was she doing alone in the woods so early in the morning? And why did she lie to their parents? Jack's efforts to unravel the truth lead to a pulse-pounding adventure that brings the Landon kids face to face with an enraged grizzly-as Jack and his sister suddenly become the...

While she studies condors in the Grand Canyon a scientist's life is threatened, and the strange, hostile, teenage computer whiz in her family's foster care might be involved.

The hawkshill sea turtle is disappearing from the waters of the Caribbean, and the Landon's are in Virgin Islands National Park to figure out why.

While lost in a tunnel at Carlsbad Cavern, thirteen-year-old Jack, eleven-year-old Ashley, and their eight-year-old foster brother, Sam, think bats and darkness are their worst problems, until they stumble across thieves.

While their mother investigates a series of bear attacks in and near Gatlinburg, Tennessee, Jack and Ashley learn about country music and Cherokee people from two new friends, one of whom is keeping a secret.