Need to Hide Certain Pages from Indexing

So, here’s the conundrum I’m running into. On the “front end” I have a site that’s fully functional to users that they can browse, etc. However, I just created a “hidden” page that’s not accessible unless you know the URL. The URL was sent to special members of our site as part of a promotion so they could get access to exclusive content. On this page I have a gallery set up that has a few hundred images posted. What I would like to be able to do is prevent both the main page (the hidden URL I sent out to people), AS WELL as the images within the gallery on the page to be hidden from the search engines as well.

As it stands, when a user clicks on an image on this hidden URL, it brings them to a new “image” page that’s still within the site, but again, is not accessible through menus etc.

In short, how to I prevent the indexing of both the main gallery page, as well as all of the subsequent image pages? Thanks a lot!

PS: I already have a plugin called Meta Robots installed that allows me to prevent indexing on certain pages, which I’ve enabled for this hidden URL page, but I’m not sure if those settings carry through to all of the images within the gallery on the page as well.

Thank you very much for your time!