The Alden children start out on a one-day mountain climbing excursion that becomes very exciting. They unearth some mysteries and some treasure and have a good time in the process.

While on a cruise with their grandfather, the Alden children help discover who is behind the mysterious troubles of the ship--disconnected phone lines, engine trouble, a man overboard--and still have fun sightseeing, eating, and swimming.

The Boxcar children uncover a mystery on a train trip from Boston to San Francisco.

Benny isn't too happy to run into his teacher during the weekend but the encounter turns out to have happy consequences.

While Henry, Jessie, Violet, and Benny help a friend fix up an old mansion filled with skeletons belonging to the doctor who once lived there, statues begin disappearing from the mansion grounds and a walking skeleton may be the culprit.

When an elderly friend is injured, the Alden children offer to help him with his window-washing business in their small town of Greenfield and agree to help him solve a riddle that has arrived in a mysterious invitation.

The Aldens visit Peggy and Doc Firmin's sheep farm and get a behind-the-scenes look at a teddy bear workshop. When a rare and valuable teddy bear disappears, it's up to the Alden children to track down the thief.

The children are staying at the home of a famous inventor who was known for her one-of-a-kind clocks. All the clocks make noise especially at midnight, when there are enough chimes, gongs, and clangs to wake the whole house up! But the clocks aren't the only sound in the house at midnight. Someone or something is making a mysterious tapping sound. Who could be inventing trouble in the old house?