Batman, Batgirl, and Robin forge an alliance with the Teenage Mutant Ninja Turtles to fight against the Turtles' sworn enemy, The Shredder, who has apparently teamed up with Ra's Al Ghul and The League of Assassins.
When things go bad in Beantown, top assassin Killer Bean is called to clean-up the mess. Detective Cromwell finds himself in the middle between Killer Bean and mob boss Cappuccino.
For their first day on the job as the new protectors of Metro City, Megamind and Minion are selling off the gadgets from their evil lair. But when one seemingly harmless "button" unleashes the gigantic robot MEGA-MEGAmind, the duo will have to resort to their old tricks to restore order.