Nate the Great solves the mystery of the missing picture.

The children and their grandfather spend the summer traveling on a train--in their own caboose.

The children, who are spending the summer in a lighthouse on the New England coast, are disturbed by a mysterious woman walking the lighthouse grounds. Jessie's dog Watch wakes up growling almost every evening at midnight, and Henry finds a puzzling note in the sand.

The Aldens climb a mountain and find a mystery! The hike up Old Flat Top was only supposed to take a day, but a dangerous rockslide changes everything to reveal a hidden cave that just may hold a legendary treasure!

Grandfather and Aunt Jane haven't spoken for years, but the children help them to once again talk to each other.

The Aldens take part in a hunt at a gem mine and discover that someone is out to sabotage the contest.

What will the Aldens discover on a vacation to a deserted island? Adapted from Gertrude Chandler Warner's story of the same name, this early reader allows children to start reading with a Boxcar Children classic.

Eva Wingdale and her class are excited about their trip to Poppy's Pumpkin Farm, where every year, there is one very large, extra special, thank-you pumpkin; but on the second day of the visit the owls find that the Thank-you Pumpkin has gone missing, and the farm animals are in an uproar -- so Eva and the other owls turn detective to solve the mystery of the missing pumpkin.

When the children uncover a strange puzzle in a friend's back yard, it's the start of a "spy game" leading to gold. But first they must make sense of an old photo and a riddle, and learn just who is behind this mystery within a mystery.

On Green Day, Cam and her classmates discuss ways to protect the environment, but when money collected for the school's new skylights disappears, Cam uses her photographic memory to solve the mystery.