Password protected page plugin

Hi,

I am looking for a plugin that allows me to protect a certain page on my blog and give access to specific users only. I am not looking for the standard way to protect a page with a single password, but a way to protect a page with a unique password linked to the email address of a user. Thus, in order to view a page a user needs to login with username (email address) and unique password), but this should not interfere with user roles already present in WordPress. The page itself should not be visible at all without the login details.

Is such a plugin available? Or how can I achieve this?

Thanks!

Mark