After the Sirens' episode at Canterlot High, Sunset Shimmer finds herself being approached by monsters that live in the human world. Living as a community by the name of the Convocation, she starts receiving requests from them to act in their behalf every now and again.
This is an episodic story following Sunset's adventures as an agent of the Convocation. You can pick it up from pretty much anywhere! The first chapter explains a few things, though.