It's summertime, and Henry and Benny are excited about their new jobs in the local department store. When a valuable vase disappears, the manager suspects the boys of causing trouble. They're innocent, but who is responsible for all the suspicious things going on? It's up to Benny to uncover the mystery. . . .

The Aldens become involved in a community theater production of "The Wizard of Oz," which is systematically and mysteriously being sabotaged.