Upon learning that The Gotham City Bank has been robbed by two invisible crooks, Commissioner Gordon attempts to contact The Dynamic Duo but is stopped by the invisible Cassandra Spellcraft, alias Dr. Cassandra, and her husband Cabala. After warning The Batman that they're helpless to stop them, they depart. While The Batman pays a visit to Gotham City Library where Barbara Gordon shows him some books on the occult sciences, Dr. Cassandra and Cabala return to their hideout where the good doctor shows Cabala her deadly Alvino-ray gun and warns Gordon that she will now try to steal the famous Mope diamond from Spiffany's Jewelry Store. The Commissioner quickly informs The Dynamic Duo; joined by Batgirl, the trio converge upon the jewelry store just as Dr. Cassandra tries to swipe the valuable gem. Turning her Alvino-ray gun on the trio, she steals their dimension, flattening them and leaving her free to steal the Mope Diamond while Cabala collects the flattened heroes and delivers them to Police Headquarters. Gordon is horrified when the three heroes slide under the office door! Chief O'Hara suggests that their only hope is to call upon the voice which answers The Batphone. Alfred Pennyworth is indeed notified of his employers' flattened condition and has them delivered to the main post office; incognito, he collects the trio and returns them to The Batcave.

Meanwhile, Dr. Cassandra and Cabala use their camouflage pills and sneak into Gotham State Penitentiary to release six of Gotham City's arch-criminals - The Joker, The Penguin, The Riddler, The Catwoman, King Tut, and Egghead! - and take them with them to their secret hideout in the basement of The Mortar And Pestle Building on Abracadabra Lane, where they're all issued camouflage pills and given a specific section of the city to rob. Back in The Batcave, Alfred recalls the Batmobile with the Remote Batcontrol and uses The 3-Dimensional Batrestorer on the trio and departs before Batgirl recognizes him. A fully-restored Teriffic Trio is notified about the prison breakout engineered by the good Dr. and Cabala, and Batman proceeds to use The Special Escaped Arch-criminal Batlocater in The Batcomputer to locate the hideout. Dr. Cassandra, Cabala and the crooks see The Terrific Trio and immediately ingest the pills, making themselves invisible and immune to aground attack. The Batman extinguishes the lights and The Trio turn the tables on the criminals, who become visible when they become unconscious.

Later, Commissioner Gordon and Chief O'Hara keep an appointment at Minerva's Mineral Spa...