The Aldens are spending their first week of summer at Camp Quest in Colorado. The children are excited to learn about fossil hunting and paleontology from renowned scientist Dr. Iris Perez. But strange events at the camp make them wonder if the legends of a bigfoot-like creature roaming the valley might be more fact than fiction. Can the Aldens help Dr. Iris figure out who or what is causing such a stir?

During a trip to Oregon, the Aldens are astonished when Watch discovers a backpack filled with valuables, a finding that compels them to learn what happened and return the backpack to its rightful owner.

The Alden children draw upon their resourcefulness to save the neighborhood firehouse from being torn down, while they also face a series of mysterious incidents connected with it.

When their favorite author fails to arrive as scheduled to speak at the local library, the Alden children investigate how he could board a train and never be seen again.

People line up around the block to buy Mama Tova's cupcakes. But who could be trying to steal her secret recipe? The Boxcar Children follow clues to a cupcake contest, where they must use their mystery-solving skills to find a thief.

The Alden children stumble upon a mystery when they enter their dog, Watch, in a contest that could lead to fame and fortune, but where things keep going wrong.

When the Alden children join a group of volunteers to fix up an old house for senior citizens, they try to explain the puzzling behavior of their coworkers as well as investigate some unusual events.

The Aldens start a business producing birthday parties and find themselves investigating a series of robberies taking place during their parties.

While visiting a Navaho Indian reservation in New Mexico, the Aldens try to save a forest under threat of development by proving it is the site of a lost, buried village, but someone is sabotaging their dig.

The Aldens participate in a three-day bicycle ride and soon find that someone seems to be intent on keeping others from completing the event.