If I rent a movie and can't watch it in the 30 days it shows on my account, am I still charged?

Hi, just wondering what would happen if I rented a movie but for some reason, something happened and I couldn't watch it at all in the 30 days it is available. I know it drops off the account, but am I charged if the movie isn't even started at all? Thanks, can't find anything in any help pages that answers this question!