Want to Add Thumbnail to Category, Search, Archive Listings

I would like to add a thumbnail image in front of each post excerpt in my category, search and archive listings.

Essentially what I want is for any post that contains an image, a thumbnail of the first image in the post should appear to the right of the excerpt when that post is listed on the category, search or archive pages.

I managed to figure out how to do this in another theme – Magazine Basic – but can’t seem to do it in the one I’m currently using: atahuelpa.

Is there a plug in that can help, or a piece of code someone would be willing to share?
Many thanks!