[Plugin: Now Reading] title tag with name of the book/author?

I’m using the nice plugin “Now Neading” from Rob (https://robm.me.uk/projects/plugins/wordpress/now-reading/). You can see it here: https://www.awakeblogger.com/book-club/barack-obama/the-audacity-of-hope-thoughts-on-reclaiming-the-american-dream-vintage/

As you can see, the title tag of this page is just the standard name of the blog. It would be nice to have the name of the book and the author in the title tag, so that search engines would find this page much better.

In the example of the “Now Reading” plugin, it calls <?php get_header(); ?> on top if the page. I think the question not only relates to this specific plugin but more to the question “How can I change the title tag in a custom page?”.