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 p

When a cougar attacks a hiker in Mesa Verde National Park, the Landons have another mystery on their hands. Jack and Ashley are used to visiting parks with thei

When Dr. Olivia Landon receives this anonymous e-mail shortly after broadcasting her controversial plan to save the condors, everyone thinks it’s a crank thre

The Landons are in the Caribbean, in Virgin Islands National Park, to figure out what is destroying the coral reefs and causing the hawksbill sea turtle to disa