In "Babes in Toyland" (okay, it's a movie / play, not a novel) where Mary Mary Quite Contrary is an heiress... but it's just an awful story
, which doesn't make much sense. So, never mind.
Most of the stories I can think of are old movies, so aren't much help, and usually someone is trying to kill off the heiress, not just abduct her. Does "Washington Square" work? I've only seen the movie, but I know it was based on a book. It sounds like what you want is something Gothic, or something like "Jane Eyre" (which for some reason, I can never remember the ending of). There's always Princess Buttercup from "Princess Bride", but she wasn't an heiress, and was abducted only to start a war. There's always "Snow White" or "Cinderella", which (if you take the Disney version) are heiresses abducted to get them out of the way.
Okay, I can see I have been anything but helpful. Sorry.
Clearly, I've been reading the wrong sort of story.
Anyway, Welcome Back!