A friendly writer with a metal detector, the mysterious inhabitants of a tower house, and the discovery of a locket in the sand are ingredients for the Aldens' latest mystery.

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' neighbor, Lina, thinks there's treasure hidden in her attic, and she wants the Aldens to help her find it. Of course, the children are eager to help search — but it appears they aren't the only ones looking for the treasure. Can the Boxcar Children discover the treasure in the attic . . . before someone else finds it first?

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

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?

The Aldens discover there's nothing more fun than a drive-in movie. But pranks and other odd things are happening at the Diamond Drive-In, and late at night, a ghost is seen walking around the empty lot. Is the old theater really haunted?

The four Alden children, aged six to fourteen, volunteer at the new recycling center in town, and help uncover who is breaking in and making a mess each night.

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.

"Henry, Jessie, Violet, and Benny used to live in a boxcar. Now they have adventures everywhere they go. At a lighthouse, the children find a mystery in the night!"

"One day in the park, the Aldens' dog, Watch, comes across a mysterious box with a note inside. 'Congratulations!' the note says. 'You've found it!' The box is part of a game called Geocaching. Soon, Henry, Jessie, Violet, and Benny are searching all over town for hidden boxes and making friends with other kids in the geocaching club. But is one of the club members a thief?" -- p. [4] of cover.