Index is still a fugitive and many powerful magical organizations and individuals want to take her to use the books in her memory, eliminating her in the process.
War between those organizations is also starting to emerge.
Index can only rely on her friend Tōma, who has always protected her, along with Misaka and other friends from the Academy.
But, let’s be honest: what counts and greatly adds to your watching experience is Biribiri in full tsundere-mode!
Edit: I made a very, very mandatory v2-patch for ep1 which you can download here: