Just finished Destroyer Angel by Nevada Barr. This is the 18th Anna Pigeon novel.

Anna is a ranger for the U.S. Parks Services. She, two of her friends and their daughters head to Minnesota for a remote camping  vacation. Anna leaves the campsite one evening to canoe on her own. Upon her return she finds her four camping companions are being held captive by, (my words) four despicable characters.  Why are these men interested in the group?  Anna keeps hidden to try to rescue her friends. As this is remote camping, there is no one else in the area and very limited resources. Oh, and they didn't bring a cell phone because the wanted to "get away from it all'. Did I mention that one of the women is a paraplegic?

This is a story of the human instinct to survive despite all odds. It is so well written, that even I was exhausted at the end of the book.

Check it out! (Sorry for the pun)
:)

http://www.goodreads.com/book/show/17934372-destroyer-angel