The book cover in your post reminds me - there was a book called "Angie's First Case" and one of the editions had cover art showing the main character and her friend in the process of untying themselves. From what I remember, she and her friend were bound, gagged and blindfolded together, and then later in the book she gets bound and gagged again.
Kind of an odd choice of cover art when you think about it, but hey, I wasn't complaining.
