While visiting the Everglades National Park with their parents, the Landon children uncover the mystery of dying manatees and learn important lessons about the natural environment.

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.

While their parents study why wolverines are disappearing from Alaska's Denali National Park, Jack and Ashley are stranded in a remote area with their mysterious new foster brother when a hit man's bullet triggers an avalanche.

The Landon family makes a trip to Death Valley National Park accompanied by a mysterious new foster child, fourteen-year-old Leesa Sherman.

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.