Batman's main storyline is complete. Catwoman is looking to leave Gotham. Two-Face has other plans. She now has to go after Two-Face and take him down.
Batman: Arkham City is the 2nd installment in the Arkham series. It was released in 2011 as a sequel to Arkham Asylum. In this storyline, Bruce Wayne is imprisoned in Arkham City. The city is a super prison built around the slums of Gotham keeping all of the decaying parts of the city inside. There's a mysterious protocol 10 going on which Batman needs to uncover. Play as Batman and Catwoman as she completes some other side tasks as well.
Watch all of RockMaster9001's Batman Arkham City Walkthroughs: Batman Arkham City Walkthrough Series