I'm reading some of the reviews for this book, and I'm kind of wondering if some of you are confusing this book for something else. All the action was relevant to the plot! And, in my opinion, action is what was lacking in many of the volumes of the series (after a certain point). This book is loaded with action, much of it truely dangerous. In many Hardy Boys books (recent ones) the enemy was so unthreatening that it was laughable. At least in this book, the villains actually do something other than sending threatening letters.
As for some of you complaining about a paper-thin plot, give me a break. This is the Hardy Boys! No books since Disappearing Floor actually had good plots!
The Disappearing Floor was (most likely) the last book actually written by Franklin W. Dixon. I know this because in the book after that, (Flying Express) the writing style was completely different, the the names of many locations changed. Also, after Disappearing Floor, the stories were no longer mysteries (Except maybe a couple,) they were action stories. So I'm wondering why you all thought this would be any different.
Yes, the story is predictable, yes, the mystery can be solved from the moment you find out about it, and yes, the plot was paper thin, but you can say that about every Hardy Boys book that came after Disappearing Floor, basically. The series has been going downhill since then, and Arctic Patrol Mystery happens to at least stand out. By itself, this book is a lackluster mystery story. But comparing it to the volumes of the series that came out before and after this....this wins.
If you want real mysteries, read the first 19 volumes of the series. If you want cool action stories that take place in many cool locations, read volumes 20 to 58. This gets 5 stars because I knew what to expect when I started reading it, and I was satisfied.