The Joker is back in Gotham City, this time with his sights set on worldwide domination. He plants rumors of an invasion from outer space, then sets out to gather the Beryllium metal needed to build an actual flying saucer. Batman picks up on his scheme and sends Alfred to check up on a stash of the metal. But when Alfred is mistaken for a mad scientist by the Joker, he is hauled off to the villain's lair along with Batgirl. The Dynamic Duo are on their way when a bomb planted by one of the Joker's henchmen goes off, leaving them unconscious, and their Batcave cut off from the rest of the world.

Dr. Cassandra and her husband Cabala are behind a string of invisible robberies, thanks to their camouflage pills. When Batman, Robin, and Batgirl attempt to stop their next theft, the crooks turn them into 2-dimensional figures with their ray gun. Dr. Cassandra then begins work on her final plan - releasing all the super criminals from prison to join her invisible force.