The Joker and his men Verdigris, Shamrock, and Chartreuse, and his moll Emerald create a flying saucer scare in Gotham City in order to prepare the people for his latest scheme: to build an actual flying saucer with the plans he obtained from a mad scientist cellmate and use it to take over the world! While The Caped Crusader and The Boy Wonder visit with Gordon (who was swamped with phone calls by concerned and frightened Gothamites), Verdigris (dressed as a little green man from Mars) plants a little green time bomb inside The Batmobile, set to detonate at midnight! The Dynamic Duo speed back to The Batcave to use The Current Criminal Activity Batdisclosure Unit, and they discover The Joker's plan to build a flying saucer, but first he must obtain a source of lightweight metal. The Batman then remembers a supply of beryllium currently stored at The Wayne Foundation Metal Research Wing and sends Alfred Pennyworth to keep an eye on it. As Batman and Robin prepare to join their butler, midnight arrives; the bomb goes off and wrecks the entire Batcave!!!!!! Meanwhile, The Harlequin of Homicidal Humor and his henchmen raid The Wayne Foundation and, mistaking Alf for a mad scientist, spirit him back to their hideout to browbeat him into building the fiendish flying saucer.
Over 8 hours later, in the battered Batcave, Batman and Robin survived the effects of the bomb, protected by their Antithermal Bat-T-shirts and finally wake up. Finding the fallout has broken every receiving device and knocked all the phones off the hooks, they make some quick repairs and try to contact Alfred, who has since completed the flying saucer; then they rev up The Batcycle, speed to Gotham Airport, switch to The Batcopter and take off in search of the saucer. Back at The Joker's hideout at The Abandoned Launching Pad Factory on Flying Circus Hill, Batgirl, who followed Joker from The Wayne Foundation and was also captured, along with Alfred, is about to be launched into orbit by The Criminal Comedian--but she foils his scheme by activating her Automatic Fuse Extinguisher in her Utility Belt. An incensed Joker immediately has The Caped Crusadress and Alfred taken aboard the saucer, and they all take off and head for outer space. Alf finally reaches The Dynamic Duo (which has kept distant pursuit in The Batcopter) on his tiny Intercosmic Two-Way Thermophone hidden inside his handkerchief and informs them that he cleverly placed some homing beryllium in the saucer, which will force it to return to the factory. As Joker begins his ultimatum from outer space, his saucer is automatically pulled back to the factory where a waiting Batman and Robin proceed to put The Fiendish Funnyman and his flunkies into orbit!