The End of the Trail is a Hardy Boys book.
[1] Biff Hooper, Phil Cohen, and Chet Morton go with the Hardy Boys on a hike up the Appalachian Trail, but things take a turn for the worse when Biff is hurt.
The boys go to Morgan's Quarry, the nearest town, for help, and find a bag of cash in the middle of the road.
Now, the Hardy Boys must find the owner, or face death.
Further suggestions might be found on the article's talk page.