The Joker has Batman and Robin restrained in a pair of electric chairs in the back of a mobile slot machine torture van. The Joker starts the slot reels spinning; if three liberty bells come up, the Dynamic Duo are freed and win $50,000; if three oranges come up they are only freed, but if three lemons come up (which according to Batman is the more likely), the Dynamic Duo will be instantly dispatched by 50,000 volts of electricity.
Though the Joker swears the slot machine itself has not been rigged, the first two reels both turn up lemons. However, just as the third reel stops on the lemon, the entire city goes dark--Gotham City has suffered a massive blackout!!! As the police approach, the Joker escapes with Susie and the Bad Pennies, leaving Batman and Robin still tied up in the back. The two patrolmen stop near the truck and find Batman and Robin inside, whom they cut loose before the power comes back on.
Back in the Batcave, they listen to the secret audio-recording they made and discover that Susie is a member of the Joker's Bad Pennies gang. Robin is heartbroken, but Batman sees it as a break and sends Robin undercover as Dick Grayson in an attempt to trick Susie into leading him to the villains’ hideout.
Now dressed as a hoodlum, Dick goes to the Easy Living Candy Store, where Susie and Nick are hanging out. Susie notices Dick, but Nick is immediately suspicious. Dick plays up being looking for a way to make a fast buck, but when Susie points out that he lives with Bruce Wayne, Dick blows it off, calling Bruce a skinflint and saying that he would even lack cigarette money if not for Alfred, so Nick gives Dick one of his own cigarettes and even lights it up, causing Dick to cough violently, but he tries to play it off claiming he had already smoked two packs today. Susie suggests that Dick could be a great help to them and very nearly drops the Joker's name before Nick interrupts her and then tips Dick off, saying that he may make a few bucks if he shows up at a certain time at the same bar with the trick jukebox. Satisfied, Dick leaves, and then Nick rebukes Susie for her ignorance, saying that he could tell right away that Dick was a phony.
The Dynamic Duo arrive at the bar at the appointed time and come under fire from the shotgun-wielding jukebox, but Batman destroys it. Robin realizes that Batman knew that the Joker was going to try and kill them, and Batman points out that Robin (as Dick) betrayed himself in the candy store by the mere fact of not being a smoker, and that Nick had to have figured out that Dick was working undercover for the police. When Robin figures out that they were pressing Susie because they knew she was part of the Joker's gang, Batman adds that once the Joker knows that they are on to her, he will waste no time disposing of her, and permanently so at that.
Unfortunately for Susie, Nick had already tipped the Joker off; the Joker instructs Susie to plant the printed answers to an important nationwide pre-college exam inside the gym's milk machine. He then gives her some perfume to put on as soon as she is finished, to which perfume, unbeknownst to Susie, he has already added a fast-acting deadly poison--NOT his customary venom. The Joker then places a large wager with a Las Vegas, Nevada-based bookmaker known as "Pete The Swede;" fifty thousand dollars on Disko Tech to beat the heavily-favored WRHS in the big basketball game that night. The Joker is delighted that he stands to win a million dollars from the wager.
At the high school, the basketball team is practicing while Susie and the other cheerleaders are rehearsing. The girls take a break and Susie secretly removes the 'out of order' sign from the freshly-rigged milk machine. Batman and Robin catch up with her outside the locker rooms and try to warn her that her life is in danger, but Susie ignores them and opens the bottle of poisoned perfume and dabs some onto herself, and when she takes a deep whiff of the contaminated cologne, she immediately falls unconscious into the arms of the Dynamic Duo; Batman quickly deduces that Susie's perfume was poisoned.
Later that night at the Joker's lair, Two-Bit informs the Joker and Nick that he saw Robin crying inconsolably as Susie's body was being driven away in a coroner's ambulance. The Joker (seemingly) is, and his two minions DEFINITELY are, momentarily saddened at Susie's (apparent) death. The Joker then gives Nick a memorial cigar, which promptly explodes when he lights it. The Joker quickly returns to his old self and, along with his Bad Pennies, he heads to the high school gym, where his scheme is about to reach its finale.
At the gym, the starting five for Woodrow Roosevelt's basketball team are finishing their warm-ups for the big game. They know of Susie's seeming fate and are determined to beat Disko Tech as a tribute. On their way to the locker room, one of the teammates notices that the 'out-of-order' sign is gone from the milk machine. One of them deposits a coin, but instead of milk, out drops a scroll of papers. They look over the sheets and quickly realize in disbelief that they are the Nationwide Pre-College Exam papers with the answers written in already; stunned, they show no signs of knowing what to do next.
At that moment, a camera flashes, and the team looks up to see the Joker, Nick, and Two-Bit with a camera having just snapped a picture of them with the incriminating evidence. The Joker and the Bad Pennies pretend that they just happened to be on school property, which they support with their taxes. The players begin to despair of disqualification, and also that if the "scrubs" replace them, then the team will be no match for Disko Tech. But Batman and Robin show up and reveal not only that they have already replaced the real exam papers in the machine with phonies, but also that they have saved Susie's life using Universal Antidote Pills in their utility belts, and that Susie, in turn, has revealed the Joker's entire scheme to them. As the ball players run for cover, the Caped Crusaders take the Bad Pennies out of circulation, and when the Joker tries to escape, Batman knocks him out with his Batarang.
At Wayne Manor, Susie is about to be driven (by chauffeur-driven limousine, per Bruce's instructions) to the Wayne Foundation Home for Delinquent Girls, which is more like a Girls' Town than a prison. The mercy shown by the court system and Bruce Wayne causes Susie to be overcome with remorse over what she has done, but Dick reminds her that it wasn't all her fault as she had a miserable childhood having been raised in a broken home. As a gesture of deep appreciation, Susie gives Dick a tender kiss on the cheek; Dick promises he will stay in touch, and Susie is on her way to the Home.
Batman battles False-Face!
The blackout in this episode (which aired in March 1966) pays an ironic homage to the Northeast Blackout of 1965 from the previous November, during which time over 30 million people in eight US states (and most of Ontario in Canada) were without power for upwards of thirteen hours.