"Holiday Knights" is the premiere episode of The New Batman Adventures. Despite being originally aired in September, this episode contains three Christmas themed vignettes, all completely unrelated to one another. The first story stars Batman in pursuit of Gotham's dames, Poison Ivy and Harley Quinn ; the following tale is about Batgirl 's confrontation with Clayface ; finally we have the Clown Prince of Crime on the loose with Batman and Robin trying to stop him.
Harley Quinn bemoans her fate to her friend, Poison Ivy, as they stay holed up in the skuzzy Gotham Hotel. With a raised eyebrow of devious foreboding, Ivy assures the rambunctious "Harl" that she has a plan that will make it "the happiest holiday ever".
Later on, at the Vreeland estate, we catch up with Bruce having a pleasant conversation with heartthrob Veronica about forthcoming vacation plans. Much to "Brucey's" chagrin, his quiet moment is interrupted by a gaggle of suitors all intent on snagging a moment with Gotham's most eligible bachelor under the mistletoe. Backing away in order to make an escape, he finds himself in the arms of a shadowy female figure who – seizing him by his necktie – plants a big one right on his kisser. Finding himself completely discombobulated as to what exactly just transpired, he makes his way outside with the intent to head home.
On his way to his car, however, he's intercepted by Poison Ivy and Harley Quinn, with a look on his face like he cannot resist their every command no matter how hard he tries. While in the car, Harley kindly reveals exactly what happened: Poison Ivy used a special lipstick laced with a chemical in order to infect Bruce, via the aforementioned kiss. They also boldly pronounce that they intend to have a night on the town at Mr. Wayne's expense. The girls shop endlessly buying clothes and jewels, all the while Bruce begrudgingly (yet uncontrollably) puts it all on his credit cards. Finally, Bruce begins building up a will as the chemical's potency begins to wane. Vocalizing his discontent, the girls decide it's time for another dose; backing away from Harley's approach, however, Bruce falls down a conveniently placed 'out of order' open elevator shaft. Believing the slip to be his last, Harley and Ivy leave Bruce for dead, yet as they turn their backs and walk away, a portentous hand reaches out of the abyss and grips the edge of the floor.
As the duo burn rubber away from Bergduffs Department Store, the silhouette of the Batman can be seen swooping after them. When Harley spots him through the back window, Ivy wastes no time in making an escape: she grabs the wheel of the car and ram raids the Wacko Toys shop. Probing through the pitch black with his flashlight, Batman soon needn't wonder where they've gone to as a huge toy soldier comes crashing down nearly upon him. Looking up, he can see them taunting him atop a citadel of toys. Not one to decline a challenge, Batman eagerly ascends the tower only to find a boxing glove by Poison Ivy and a wooden sledge hammer from Harley Quinn. Plummeting to the bottom, the girls cannot resist a gloat as they make – what they believe will be – their exit. But the quick minded Batman has other plans: he uses his grappling hook to snag the base of a massive Christmas tree, which he then yanks hard, causing it to topple over directly on the would-be escapees.
In Mayfields Department Store, Barbara is just purchasing a new tie for her father when all of a sudden an ear-piercing wail cuts through the air. The shop attendant comments on how they've been crying all day, at which point we see why: Harvey Bullock is playing Santa. With his partner, Montoya , he's on a stakeout. Bullock, showing rare sensitivity, comforts a young girl who's father he put in prison, and winds up giving her cash to soothe her Christmastime woes.
Barbara, walking through the store, happens to spot a child shoplifting, but when she tries to apprehend him, his clothes and hand seem to dissolve into nothing. Then, Montoya gets a call through her earpiece that detectives are in pursuit of four child bandits in the store. Just when the children seem to be trapped, they meld! Moments later the truth is revealed: Clayface! He begins tearing up the place and no one can stop him, that is, until Barbara gets changed into her Batgirl outfit and delivers a blow to the head the sends him crashing out the window and into the skating rink below. Montoya and Bullock arrive on the scene and with a little guidance from Barbara, succeed in halting the giant shapeshifter by way of electrocution.
In Commissioner Gordon's office, Batman and Robin have just reviewed a taped broadcast by the Joker, who reveals some good news and bad news: the good news is that for the next year, he will not kill anyone; the bad news is that he intends to make up for the loss in activity that very night. Gordon tells Batman the only murder that day was a GothCorp scientist who specialized in sonics. This Dr. Erikson had been working on a sonic based weapon powerful enough to kill anyone in 'earshot'. Using some rudimentary deductive skills, Batman concludes that the New Year's Day countdown at Gotham Square is assuredly the place where the Joker will set off the bomb.
Indeed, the Joker is setting up, and Batman is close at hand, but – always with a trick up his sleeve – the Joker has prepared a mass of plastic joker masks in order to help him blend in with the crowd. Batman is not amused. Using his 'Batnoculars', he easily spies the real Joker (with a huge clown wearing ear muffs on either side of him) playing the piano on stage. So just before swooping in, he makes his presence known with a well-timed Batarang to the head, removing the Joker's ear muffs. Then, instead of going after the Joker directly, Batman and Robin take out the muscle on either side of him. This seemingly simple task, however, proves to be too much for the caped crusaders and they find themselves in the clutches of the Clown Prince of Crime.
As the bell is rising to ring in the New Year, the Joker is having himself one final gloat by standing next to Batman with a bottle of champagne. The ever-alert Dark Knight snatches the bottle and sprays it all over the controls, shorting the wires and eventually exploding the bell's pulley, resulting in a falling, massively heavy bell. As luck would have it, the giant object lands right on the Joker (who comically follows it up with a small "ouch").
A few hours after midnight (January 1), Police Commissioner Gordon enters a small tavern and has a seat, while the barkeep ushers out the remnants of the punters. He speculates that "he" might not show due to the hectic day "he's" had, but the Commissioner is sure he will show so not to break tradition. Naturally, it's Batman who they're talking about and who makes an entrance from the kitchen. He sits; they chat for about ten seconds; he slips away like a shadow, leaving money for the bill behind. Gordon, surprised, swears that one day he'll beat him to the check, then heads home with a swinging Bat close behind him.
Clayface's return in this episode is not explained until the subsequent episode "Growing Pains ", in which Batman and Robin express shock to see him alive and well after Batman watched him dissolve in the ocean at the end of Batman: The Animated Series , "Mudslide ". As Batgirl does not seem surprised to see him, it is possible that she is unaware of the events of that earlier episode, or that this episode takes place after "Growing Pains".