Calling an image from the theme directory

How do I call an image that is my template directory?

The image is in my template directory in a folder called img.

I want to call the image from within a template file.

So far I have tried both get_template(), and get_template_directory(). The first doesn’t go far enough and just appends /template_directory to the url. The later goes too far back to all the way to my server root.

What’s more, I need to call it from within some existing php. Here’s the extract that’s not working for me.

echo '<div class="story-scroll-text"><p>Scroll down to continue<p></div><img src="'. get_template(). '/img/scrolldownicon.png">';

I’m pretty confused over what should be a super simple task