Bill is skeptical of Roger's theory about the sabotage, which is so much like when Sandy questions Ken's theories in the Ken Holt series.
Near the beginning of this book, we learn that the boys helped with the smuggling case last summer. This means that around one year has passed between the two books.
When I read the Ken Holt books, I noticed that everyone drinks coffee, including Ken and Sandy. In these books, I notice that all of the men smoke. Naturally, Roger and Bill don't smoke, but give them a few years, and they, too, will smoke like all of the men.
In Chapter 7, Roger and Bill's new friend, Diego, tells them about how some people in Colorado don't seem to like Diego because he is Mexican. Roger thinks that Diego's belief is nonsense until he remembers how he at first didn't like a boy at school who friends said didn't belong and wasn't worthy of them. Roger "had unthinkingly accepted the verdict of a group of older boys who called Mike a 'Hunky' and dismissed him immediately as unworthy of their gang. People don't like foreigners. Sure it was crazy. But he knew it was true, sometimes."
I had never heard the term "Hunky," although I realized it had to be an ethnic or racial slur. I looked it up and learned that it is a derogatory word for immigrants of Slovakian descent. I then made the connection between "Hungarian" and "Hunky." Now I understand. I learn so much from reading books.
From page 78:
There was an awkwardness between them now, and in a way he wished that Diego hadn't spoken. In another way he was glad he had. Because if you didn't know about things like that, how could you do anything about them?This type of passage is atypical of older series books. I am impressed, but I am also struck by how little things have changed in the last 69 years.
I thoroughly enjoyed this book. Roger and Bill do lots of sleuthing in interesting places, including an old ghost town and an old mine. Part of the scene in the mine plays out very similar to a scene in the Ken Holt book, The Mystery of Gallows Cliff.