Gotham City

All the heroes and vigilantes who were part of the Justice League have vanished: Superman, Batman, Wonder Woman, Flash, Martian Manhunter, Black Canary, Green Arrow, Aquaman, Green Lantern, Shazam, Cyborg, Zatanna—they're all gone.

Reason for the disappearance: they were taken to a prison created by Superman's father where there is no sun or rights; in fact, even Superman himself has no powers there. So, when the League arrived, everyone became powerless. Superman's father created that prison planet to ensure a place from which no one could escape, as only those with El blood can open it. To give an example, a few hours there are equivalent to 3 months on Earth.

Because of this, heroes like Kid Flash, Wonder Girl, Starfire, Raven, Aqualad, Miss Martian, Superboy, Beast Boy, Robin, Artemis, XS/Flash's daughter, Red Robin, etc., remained and were trying to protect the cities.

Batgirl tried to take care of Gotham, but she couldn't and was captured by the Joker. Now she is tied to a chair on an improvised stage with everyone in Gotham watching, either in person or from home. Many were captured there; Commissioner Gordon and several police officers were imprisoned, while others were on the surrounding rooftops trying to aim their weapons, while the Joker, Mr. Freeze, The Riddler, Harley Quinn, Cheetah, and Penguin enjoyed everything from the best seats in the house.

The city is in chaos: police officers tied up, others with no options, citizens terrified, and Batgirl scared, though she won't admit it.

The idea is to create a hero to save Batgirl.