The adventures of the four Alden children as they investigate a mystery that took place in the yellow house on Surprise Island many years before.

The adventures of the four Alden children as they spend a summer vacation on their very own island, purchased by Grandfather's father years ago.

When the Aldens spend the summer riding on a train, they get to live in a train car once again - this time, they're staying in Caboose No. 777. The number is hard to forget, and indeed, the children meet people at each stop who seem to know it well. It turns out Caboose No. 777 has an unusual past - one that comes with its very own mystery!

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!

The Alden children, isolated in a storm at a small bus station, are led into a mystery centering on a polluted river.

While on bicycle trip to their aunt's farm, the four Aldens help solve a mystery.

When the Alden children accompany their grandfather to the Snow Haven Lodge, a series of odd occurrences threaten to disrupt the annual winter games

While the Aldens' efforts to raise money for a new hospital wing are being sabotaged by nasty tricks, they find their attempts to befriend the new girl Beth frustrated by her strange behavior

"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." --

The Alden children, snowbound in a vacation cabin, discover adventure in surrounding wild life, three children they find in the snow, and a search for a lost recipe.