Heidi is only five when she is taken to live with her grandfather, known as Uncle Alp, in the Swiss Mountains. Notorious in the village for his gloomy outlook and reclusive nature, Uncle Alp nevertheless comes to love little Heidi, and she him. Just as Heidi begins to grow fond of her new mountain family and friends, she is suddenly taken to Frankfurt to be a companion to Clara, an invalid. Although she brings great joy into Clara's life, Heidi pines...

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

A young Canadian visitor helps the Alden family solve a mystery involving a lost coin collection.

Two brothers take summer jobs at a department store where a series of peculiar events brings them under suspicion.

The orphan Madeline catches a thief and makes a friend in Rome.

While helping their grandfather prepare for Greenfield's Winter Festival, the Alden children uncover a mystery surrounding the statue in the town square.

When the Aldens visit their friend Fran in Wisconsin, they can't wait to hear her tell the story of the runaway ghost. Fran's family ghost hasn't been spotted in years, but the Aldens still shiver at the spooky tale of the ghost's bell clanging after dark. Then Violet hears a mysterious ringing in the middle of the night and the children start to wonder--could the runaway ghost be back?

Nikolai, a bear who lives in the orphanage in Novosibirsk, Russia, does not seem to fit in until the day some visitors arrive from America.

While visiting the seaport town of Ragged Cove, Massachusetts, the Alden children find the ship's log of the Flying Cloud, shipwrecked in 1869, supposedly during a mutiny.