Gotham City is hosting a comedy festival, and The Joker is determined to take first prize! He's hypnotized the crowd with a new face filter app that has everyone laughing... and laughing and laughing. Batgirl and Supergirl swoop in to foil the forced fun. But the Super-Villain has more tricks up his sleeve and another terrible invention: a bubble blower whose blasts can slow down even the Girl of Steel! Can the Super Heroes put an end to the chaotic clown show?