At Hamilton High, students excitedly crowd around Chelsea, who removes her sunglasses to reveal she now has cat eyes. Chelsea passes around business cards from the Chimera Institute, a business that splices people's DNA with animal DNA. Terry is skeptical about this due to the controversy and the city trying to shut it down, but Dana brushes this off and says to keep an open mind.

Later in the Batcave, Terry and Bruce watch a newscast, where Dr. Cuvier, head of the Chimera Institute and a splicer himself, insists splicing is "safe, reversible, and more importantly, utterly beautiful." Bruce fears something bad will come of this. And knowing from his experience of people trying to combine animal and human DNA go horribly wrong, he has every right to be. Next morning, Terry's brother Matt, wearing a wolf costume, scares him out of bed. As Terry chases him out of his room, Matt asks their mother if he can be spliced; Mary says no. Terry jokingly refers to Mary's tattoo from her "wild teen years" to which she says is different from "having antlers stuck on your head." Matt then says Terry is already a donkey and Terry angrily tells him he is lucky Terry is late for school.

On a vertical train, a newscast shows DA Sam Young announcing his plan to outlaw splicing completely because it increases aggressive behavior. Just then, Ramrod, a teenager spliced with ram DNA, slams the screen. He and King Snake, another splicer, cause trouble, saying splicing is the future, but Terry fights them off, earning the applause of bystanders.

Terry takes Dana to the Chimera Institute to investigate, and sees Ramrod and King Snake demand to speak with Dr. Cuvier. In his lab, Cuvier decides to have Young killed. Batman watches, but Tigress smells him and they capture him and Cuvier injects him with a special serum prepared just for him. When he escapes, he feels strange as Cuvier attacks him with his claws. He flies off to save Young.

At Sam's house, Barbara tells him he should relax, but he is determined to put Cuvier out of business. Suddenly, Ramrod, King Snake, and Tigress break in and attack. Batman arrives, violently beats the splicers and starts foaming at the mouth. Losing control, he rushes back to the Batcave. Barbara calls up Bruce to warn him of his condition, but Terry arrives, now in the form of a Man-Bat. In the struggle, Bruce manages to dart him with an antidote. Terry wakes up to a growling Ace and learns Cuvier spliced him with an overdose of vampire bat serum and that Young survived. The authorities are now after Cuvier, who has gone into hiding. Bruce notices one of Cuvier's claws on Terry. Using the claw's scent, Batman has Ace track Cuvier to Carmine's Taxidermy Studio.

Tigress smells Batman again and the thugs attack him. As Batman fights them off, Cuvier injects himself with various DNA doses. Batman manages to subdue and cure his attackers before heading for Cuvier. Using several animal serums, Cuvier has now mutated into a "true chimera" and proves a powerful foe. Batman injects him with several more DNA tubes, and Dr. Cuvier mutates into a giant creature that no longer resembles any living being. The creature captures Batman and nearly eats him, but Ace breaks in and attacks. The creature grabs Ace, but Batman saves him. The creature hits a power cable and ignites some gasoline. Batman and Ace escape, and Cuvier likely dies in the explosion.

Later, Barbara thanks Terry for his help but advises him that the costumed life isn't worth it and has few rewards. Since Ace has shown himself to be a true Canine Companion, Terry replies that "sometimes the small rewards are the best ones."

Tropes:

• AcCENT upon the Wrong SylLABle: The word chimera is pronounced as "shi-mera", though the technical pronunciation is actually "kai-mera." While the name for the splicing company may have been called "shi-mera" for fashionable preferences, Cuvier calls himself an actual chimera using the "shi" substitute.
• All There in the Script: The names of the three splicers (Ramrod, King Cobra, and Tigress) working for Dr. Cuvier are only given in the credits.
• And There Was Much Rejoicing: Terry effortlessly making short work of two Splicers (after the pair boasted their superiority) caused some nearby patrons to cheer.
• Animal Eyes: Provides the trope picture from when Chelsea is revealed to have literal cat-eyes due to undergoing a splicer treatment.
• Ask a Stupid Question...: After his request to spliced is shot down, Matt asks his mother if he can get a tattoo instead. Mary's response to this is dropping his wolf mask on his head backwards.
• Bad Boss: Cuvier takes out his rage on Ramrod for failing to kill DA Young and leaving a witness in the attempt by savagely beating him.
• Bat People: Terry is spliced with a vampire bat serum, which turns him into a Man-Bat.
• Beast Man: Invokes the gene-splicing arm of this trope, oddly enough as a popular fad among teens ranging from Animal Eyes and noticeable horns, scales, fangs all the way to a humanoid chimera and repulsive mass of mixed-up flesh.
• Being Good Sucks: Downplayed. Barbara tries to warn Terry that being Batman isn't guaranteed to be worthwhile, as the stakes can be high and the rewards are small. But in light of Ace having bonded with him during the climatic fight, Terry voices that the small rewards are best.
• Bio-Augmentation: The episode deals with Terry fighting a group of teenagers who were spliced with animal DNA to take on certain animal traits. Other splicers are seen throughout the series.
• Body Horror: Terry involuntarily becomes a Man-Bat until he gets better. However, the really bad part is when, after splicing becomes illegal since it makes people more aggressive, Batman goes to confront Cuvier, who then turns himself into some weird hawk-tiger-snake thing and after knocking away Terry's gun filled with the mutagen cure, Terry starts sticking Cuvier with multiple syringes, reducing him to a disgusting mash-up monster.
• Bond Villain Stupidity: Cuvier, rather than just killing Batman when he has the chance, instead decides to "splice" him and then try to kill him. Similarly, when Batman stops Ramrod, Tigress, and King Cobra from killing DA Young and beats them senseless, they leave, believing that the "psycho bat" will finish the job for them; instead, Terry manages to Resist the Beast long enough to get back to Bruce and get help.
• Drugs Are Bad: The episode primarily revolved around a body-modification moral, the genetic splicing served as a metaphor for cosmetic surgery, tattoos, and piercings, but the process was addictive, mind-altering, and administered through injections.
• Early-Bird Cameo: This episode marks the first appearance of Max Gibson, though she's not properly introduced until later episodes.
• Eldritch Transformation: Cuvier's final shape is...definitely not a kid-friendly case.
• Emerging from the Shadows: After being spliced by Cuvier and saving Barbara and DA Young, Terry goes back to the Batcave. First, we see a massive silhouette of Batman...and then Terry throws his mask at Bruce's feet and comes into the light, revealing he's become a man-bat.
  Terry: Bruce! Help...me!
• Evil-Detecting Dog: When Barbara tries to warn Bruce about what's happening, Ace starts barking like crazy. The transformed Terry has entered the Batcave.
• Family-Unfriendly Death: The episode ended with Batman injecting Cuvier with so much animal DNA that he mutated into a gigantic blob-crab-monster. The transformation is not what kills him — that may have been Terry stabbing him with his own stinger-like tail — but he ends up blowing the place up in his death throes.
• Fighting from the Inside: Even after he was spliced, Batman manages to rescue the District Attorney from Cuvier's goons. It was after he fought them off that he started losing control.
• Fire-Forged Friends: This is where Ace starts treating Terry like his second owner, after the two fight Cuvier together.
• Former Teen Rebel: Mary McGinnis, according to Terry.
• Half-Human Hybrid: The Splicers, who got that way thanks to LEGO Genetics.
• I Just Want to Be Special: Implied with the splicers, what with their harassment of everyday citizens, and called them "norms" derisively, to Ramrod's protest when Batman cures them that "[he's] not going back to being a nobody."
• I Resemble That Remark!: Ramrod takes issue with a news story about claims splicing increases aggression, and expresses his discontentment by violently smashing the screen with his head.
• I'm a Humanitarian: Cuvier tries to eat Terry after his overdose. Though it's likely that Cuvier doesn't qualify as human anymore.
• Immediate Self-Contradiction: One of the teenagers being interviewed tries to justify splicing as "establishing myself as an individual" and then immediately follows up with "just like all my friends" to which we pan over to a group of people with completely identical modifications.
• LEGO Genetics: The Splicers have had their DNA spliced with different animal DNA, turning them into Half Human Hybrids. Terry is turned into a literal Bat-Man (a la the Man-Bat) at one point, but it is easily reversible. Splicing is made illegal, but at first was perfectly legal and akin to body piercing and tattooing.
• Nature Is Not a Toy: Splicing has become a popular fad with Gotham City’s youth, including many students at Terry’s high school, being spearheaded by Dr. Cuvier. While some of the modifications are purely cosmetic, others include enhanced strength, reflexes and senses in addition to giving them a more animal-like appearance. Cuvier imbues himself with multiple doses in his final confrontation with Terry, who exploits the rapid physical changes the splicing brings by dosing Cuvier with more modifications than he can handle, turning him into a monstrous, giant Humanoid Abomination with crab-like pincers for hands and tentacles, the latter of which Terry uses to wrap and pin Cuvier down just before his lab explodes (though Terry manages to escape).
• Neck Lift: Dr. Cuvier does this to Ramrod for failing to kill DA Young. When Ramrod protests that Batman got in the way, Cuvier throws him over a railing.
• Nice Job Fixing It, Villain!: After Batman was subdued, Dr. Cuvier gave him an overdose of bat DNA in order for him to be turned into a mindless creature and thus out of his way. Problem is, Batman breaks free before the transformation fully kicks in, giving him the extra strength to beat down Cuvier's three Splicers at once and save DA Young.
• No-Holds-Barred Beatdown: After being transformed, Batman does this to one of the Splicers.
• No Transhumanism Allowed: Splicing is highly controversial in-universe, and by the end is outright made illegal.
• The Nose Knows: Terry finds Cuvier by having Ace get his scent with the claw that was torn off in the fight.
• Oh, Crap!: Ramrod in response to Batman's increased aggression. He gets a No-Holds-Barred Beatdown shortly afterwards.
• Parental Hypocrisy: Terry briefly calls his mom out by mentioning her tattoo after she speaks negatively of splicing. (And he may have a point there; if it had been only a fad, it would have been far less permanent than body art.)
• Phlebotinum Overdose: Terry has Cuvier overdose on his splicing injections.
• Power-Upgrading Deformation: The splicers used genetic engineering to become Half Human Hybrids, which generally while animalistic weren't ugly. When their boss fights Terry, he takes a boatload of them and goes One-Winged Angel...until Terry gives him a second round of drugs which pushes him into Clipped-Wing Angel.
• Pun: After Dr. Cuvier turns into a One-Winged Angel mopping the floor with Batman:
  Dr. Cuvier: Now you face a true chimera! You bring out the beast in me!
• Resist the Beast: Cuvier splices Batman with vampire bat DNA, after which Batman escapes and goes to DA Young's house to save him. As he begins to transform, he brutally attacks the thugs and drives them off before advancing on Barbara, snapping out of it, and escaping. By the time he makes it back to Bruce, he's become a giant Man-Bat and has just enough self-control left to beg Bruce for help before he snaps.
• Shout-Out: The scene where Cuvier starts mutating after Terry injects him with various animal DNA, is shot almost exactly like Tetsuo’s mutation in AKIRA.
• Silver Fox: Ramrod briefly hits on Barbara Gordon.
• Villain Ball: Cuvier's big evil plan to keep splicing from getting outlawed is to... send spliced people to kill D.A. Young, who’s leading the move to outlaw it. How that would, in any way, accomplish anything other than prove every criticism against splicing to be valid and turn the public more against it than ever, not to mention send Commissioner Gordon (Young's wife) on a Roaring Rampage of Revenge hell-bent on avenging her murdered husband, is anyone's guess. He even rants at his goons for "ruining" his plans when the police raid his lab and begin hunting him after the assassination attempt fails... as if the police wouldn't have done that if the assassination had succeeded either.
• You're Insane!: Batman tells Cuvier this.
  Batman: Have you considered checking into Arkham for a little R&R, doc? Because, quite frankly, you're nuts.