Feature images stretched to container size only

Hello, I’m trying to determine a way to either hide the feature image from pages or somehow make them so they are not stretched out to the width of the divider. It seems the Aegaeus theme doesn’t offer a feature to adjust the size of feature images & the theme automatically stretches it across the divider, which results in huge photos at the top of the page. I would simply delete them, but I’m re-structuring my site with grids and the thumbnails for the grids are generated by feature images. I’ve tried adding several plug-ins (Hide Feature Image, Remove Featured Image, Simple Size Images) and none have worked. With the first 2, I tried the hide images from all pages option as well as the hide from individual pages option. I also tried removing the image & adding it again in case the plug-ins didn’t address previous images (tried in various order of steps). The plug-ins still didn’t work. My website is http://www.buzzworthytattoo.com. Here’s an example page:
http://www.buzzworthytattoo.com/tattoo-history-research-articles/tom-riley-the-making-of-a-tattooist/