The Alden children travel on a Mississippi paddle-wheel steamer to visit an old family friend in his cabin near Hannibal, Missouri, and try to discover who is responsible for the mysterious activities near the house

While staying at the Crooked House, the family home of their housekeeper Mrs. McGregor, the Aldens try to solve a riddle that will lead them to a hidden treasure

When the Alden children go camping on Blizzard Mountain, a place said to be inhabited by a ghost looking for buried treasure, they begin to think someone or something is trying to scare them off

"The Aldens find a hidden time capsule! Inside is a journal with clues to a treasure hunt. Who wrote the journal? And after a hundred years, can the Boxcar Children find the treasure?"--Back cover.

A family starts out on a one-day mountain climbing excursion that becomes very exciting. In fact, it becomes an adventure for the former "boxcar" family. They unearth some mysteries and have a fine time in the process.