The mask is the same of the movie.
Now the mask that is in a museum in Gotham City ends up in the hands of Batman's archenemy, the Joker, it will stop at your hands by chance, your comrade accidentally triggers the alarm to catch her and they flee with her in the hands.
Joker gets irritated and pushes the mask against the face of the man who soon transforms. Batman appears suddenly and Joker turns into Big-Head. As Batman is no match for the new Joker, he uses his psychology and manages to trick Joker into removing the Mask claiming that the villain is not so funny in that way, Joker has a small crisis with himself and ends up removing the mask at that time Batman attacks, and Joker is arrested.
Lieutenant Kellaway appears and asks that Batman give him the mask claiming that he will get rid of her forever, Batman agrees and Kellaway goes to the tomb of Stanley Ipkiss, opens the tomb and throws the mask next to Stanley's body, in fact, it was him that started it all.