I need help finding a book about a kidnap

[snootycow]

Hello, I'm new here so i hope i'm posting in the correct category. I need help finding a book I read a few years ago, i can't remember the title or the author but it was about a young girl who was kidnapped by a couple and held against her will for a considerable amount of time, most of the time in a coffin like box. I'm pretty sure it was based on a true story. Does anybody have any ideas what this could be? it's driving me nuts!
Thanks