I think this is one of the most exciting bondage scenarios.  The villain or villains are confident enough to leave his/her captive where everyone can see her.  Your heroine is helpless bound, but no one realizes it.  Her bondage could been hidden by clothing (a coat and headscarf) or perhaps she is gagged with clear tape or with flesh colored tape and painted on lips...your choice.  I would add that in my scenario, my heroine's panties would be pulled down (not suggesting anything here) for the purpose of humiliation and embarrassment if and when she is discovered.  [The panties themselves still might be hidden unless someone goes to untie her.]  That is, she would prefer to get untied herself and not to be rescued or at least to minimize her desire to be rescued.

So where would be the most exciting and unexpected place to leave her?  

Tell me in poll #22.  Some of these have been used on TV shows, etc.  What location would you choose.  Tell me why in the comments.