Among my earliest series book reading picks were The Hardy Boys. Adventures with Frank and Joe led me on many thrilling journeys that included haunted houses, hidden treasure, and sneaky spies. I had several of the blue PC editions from the sixties, and many were probably original text PC's that I am sorry have disappeared over the years.
I am especially fond of the original text version of The Secret of the Lost Tunnel. The boys travel south in an effort to vindicate the good name of a Confederate Civil War general. He was accused of stealing gold from a bank, and the boys work hard to help clear up the mystery. I have only read the original text version, but upon searching the title on Google, the revised text appears to be a condensed version of the same story.
I love Civil War stories, and anything set in the South. Ghostwriter Andrew Svensen did a great job, in my opinion, fleshing out the characters and creating an interesting read. As a child, I enjoyed books that had boys investigating abandoned mines and tunnels. We had large drainage pipes in our community, and my friends and I would light candles and explore the underground maze of pipes. It was real life Tom Sawyer type adventure! We never ran across Injun Joe, thank goodness!
The Hardy Boys series continues to delight children, and the books continue to sell on Ebay and Bonanzle. I have several nice copies in my Bonanzle Booth, and of course the revised text books are available in the cheap Flashlight editions. If you don't remember this one, pick up a copy and read it! You'll enjoy the mystery.