@SamuelEth is right, creating a page to handle this (with rewrites) could be the way to go.
Another alternative would be registering a custom post type of my-plugin(with the admin UI setting off since you don’t want user access to it)…
…and dynamically detecting and handling calls to that, the advantage being the rewrite is done for you somewhat. Because of that you can probably hook in to check the query is of your custom post type, and if so modify the query and/or output to point to generate content you want.