Handle custom URL with plugin

Replies: 0

I’ve tryed to search info but found nothing.
The question is, I want to develop a plugin, which can display specific content on custom chosen URLs. For example, http://localhost/wordpress/topics will display the topic list.
No page with slug “topic” exists, so WP just giving me 404 page. How to handle this, and make plugin be able to display specific content on non-existing in WP URLs?