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 hunted.

The Landon family is Southbound—headed for Florida to investigate a mysterious illness plaguing endangered manatees in Everglades National Park. Jack, Ashley, and their friend Bridger soon find themselves in deadly waters with a seven-foot shark, an injured manatee—and a mystery to solve. Who was the stranger in the speedboat who snatched Jack's camera? And what does he have to do with the manatees? Join the heart-stopping chase through a maze of mangrove islands to find out!

A baby whale is the latest mammal stranded on the beaches of Acadia National Park. When the Landons run to get help, they don’t notice Bindy Callister slip away. When they track her down, she’s acting strange—she knows the strandings are no accident. She even knows those responsible. But she’s too scared to tell. Time is running out; and now the kids too are in real danger—unless Bindy talks!

This thrilling series roars back to life with the release of Mystery #13, Night of the Black Bear. Something very strange is going on in Great Smoky Mountains National Park. A teenage girl is the latest victim in a growing number of bear attacks. Officials must figure out what's causing the bizarre bear behavior or close the park. Can the Landons help? Soon Jack and Ashley are searching for answers with their new friends Yonah Firekiller, a 16-year-old Cherokee boy, and 14-year-old Merle Chapman, whose family once lived on park land. But a heated argument over ancestral land rights puts the Landon kids in the middle of a clash of cultures. Tensions mount when Merle is caught in a lie—a lie that leads straight to the heart-pounding solution. This breathtaking new adventure features an afterword by a park naturalist on black bear behavior and the problems caused by tourists feeding wildlife. Night of the Black Bear is a fast-paced narrative treat filled with vivid descriptions of the natural, scientific, and cultural phenomena of Great Smoky Mountains National Park; a page-turner that will put this popular National Park high on the vacation wish-list of all young readers. National Geographic supports K-12 educators with ELA Common Core Resources. Visit www.natgeoed.org/commoncore for more information.

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 their wildlife veterinarian mother and photographer father, but this time their hands are full with a foster child called Lucky Deal. As Lucky and Jack become friends, Ashley becomes suspicious: What did Lucky take from the burn site? Who did she call in the night? In a midnight showdown at Spruce Tree House, Jack realizes there's more to fear than a killer cat. Cliff-Hanger weaves Native American folklore, natural science, and geography into a heart-pounding thriller. The afterword by Will Morris, Chief of Interpretation and Visitor Services at Mesa Verde, outlines the dangers of cougar attacks and the need to protect wild animals. National Geographic supports K-12 educators with ELA Common Core Resources. Visit www.natgeoed.org/commoncore for more information.

In this fast-paced adventure, the Landons trail a wounded wolf in Yellowstone National Park. The park is abuzz with rumors of a wolf attack. Meanwhile, a killer stalks the woods. Unaware of the danger, Jack and Ashley are more concerned about rebellious teenage foster child, Troy Haverson. From the opening moments at Old Faithful through 48 action-packed hours, the tension builds: What is lodged in the wolf's radio collar? And what is the meaning of the Native American story of Sin-a-Wavi? A heady mix of suspense, adventure, and moments of tenderness lure readers into this story of kids discovering the natural world. The book's afterword, by Yellowstone's Michael K. Phillips, explores the park's Wolf Restoration Program. National Geographic supports K-12 educators with ELA Common Core Resources. Visit www.natgeoed.org/commoncore for more information.

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 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 disappear. Jack and Ashley find themselves hopelessly entangled in the mysterious life of Forrest Winthrop IV, the adopted son of a U.S. diplomat. Why is he so anxious to save an island woman named Cimmaron? What secret do they share? Follow the action to Jumbie Bay and see what the full moon reveals.

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 threat except Dr. Landon’s daughter Ashley. She’s sure it’s the handiwork of Morgan Rogers, self-proclaimed anarchist and computer geek. Suspicions mount when the death threat almost becomes a reality, and Morgan is the only witness. Is he innocent or guilty? Journey into the maze of Morgan’s cyberworld and find out!