How to display the Images from a Post in a Lightbox without the Post itself?

Apparently what I’m trying to do is either too easy or too weird for anyone to have done that publicly…

I’m setting up this event-site and the owner wants to send emails with images which are then displayed in an archive on the site. That is the easy part…

The tricky one seems to be the display of those, I want a single Thumbnail per post/event, if someone clicks on that it should show a lightbox with the thumb and the other containing images, without leaving the page you’re on. So that I can have the 6 most recent events listed and if you click on any of those, it should read the images from that post and display directly.

I’m using “simple lightbox” for the effect, but that only works inside the post.

I really tried searching the web for answers, but it’s either galleries that display all images on the page and not only one, or something else is way off…

Hopefully that explanation is somewhat understandable and someone is willing to help me on that.

Thanks in advance,
M.