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

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.

Henry, Jessie, Violet, and Benny Alden are on another summer trip to visit Aunt Jane at Mystery Ranch. They're thrilled to find their friend Mike Wood lives in the bustling new town near the ranch. But one night, Mike's house burns down and he is blamed for starting the fire!

Benny anticipates making friends with the new kid down the street, but when he finds out that she's a girl, he is very disappointed.

When Benny Alden decides he wants to go into business like his grandfather, his first several attempts don't quite work out.

Violet and Jessie begin an adventure out West when they journey to Centerville to keep Aunt Jane company on the family ranch.