The enchantress Circe transforms Wonder Woman into a pig as revenge against Diana's mother. Batman and Zatanna work together to return her to normal, while trying to find the escaped "Wonder Pig."

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!!This episode includes examples of:
* AffablyEvil: After getting her revenge on Hippolyta by cursing her daughter Wonder Woman, Circe spends the rest of the episode singing at a lounge with a captive audience, rather than cause more mayhem with her magic.
* ArtEvolution: Zatanna's post-BTAS redesign (which was briefly seen in an archival photograph in ''Batman Beyond'''s "Out of the Past") is further revamped for her debut on ''Justice League''.
* AuthorAppeal: Paul Dini, Zatanna, you know how it goes.
* BaitAndSwitch: When Batman asks Circe what it will take for her to undo the curse on Diana, it initially seems as though only his SecretIdentity will fit the bill. It turns out there's something else that fits that Batman has worked hard to hide, and can't regain once he's given it away: the sound of his smooth singing voice.
* TheComicallySerious: Batman is, well... [[TheStoic Batman]]. He ends up [[ItMakesSenseInContext singing the blues at a club]].
* ComicallySmallDemand: Batman resorts to negotiating with Circe to get her to change Diana back to normal. Circe ominously spells out that whatever Bruce has to give up in exchange will shatter his soul. She wants him to... sing in a nightclub. Knowing Batman, he did have to surrender a lot of dignity for that one.
* ContinuityNod:
** Zatanna knows Batman's SecretIdentity, as he revealed it to her way back in [[Recap/BatmanTheAnimatedSeriesE54Zatanna her debut episode]].
** Batman and Wonder Woman are staking out the Penguin's Iceberg Lounge.
** The song Batman sings, "Am I Blue", has appeared in the DCAU before. Barbara Gordon's roommate has a record of it playing in the background in a scene in ''WesternAnimation/BatmanAndMisterFreezeSubZero''.
** Batman is clearly remembering the events of “Starcrossed”, since his main reason for not pursuing a relationship is that dating within the team always leads to disaster.
* CrazyPrepared: After revealing his secret singing talent, Batman tells Zatanna that he picked up the skill in order to go undercover as a lounge singer for a criminal investigation.
* DealWithTheDevil: PlayedForLaughs Batman realizes that only Circe can lift the spell on Diana.
-->'''Batman:''' What would I have to give to make you lift your spell on Diana? \\
'''Circe:''' Well, now you're getting interesting. I want something from you that's very precious. Something you've worked ''very hard'' to conceal. Something when gone, you can never regain. Something ''soul-shattering''...
-->''(cut to Batman at a mike)''
* EvilChef: While Batman and Zatanna track down and try to bargain with Circe, Wonder Pig ends up getting confused for a regular pig and sent to a slaughter house, where the butchers in charge are ''very'' determined to not let even one oddly self-aware pig escape.
* FamedInStory: Before Wonder Woman can introduce Circe, Batman states he's already read the ''Literature/TheOdyssey.''
* ForcedTransformation: Aside from the titular case, Circe turns the patrons of the Amphitheatre into wild animals to attack Batman and Zatanna.
* GoKartingWithBowser: Both Zatanna and Circe end up enjoying Batman's "secret".
* HeroicSacrifice: A non-fatal, played for laughs example - to get Circe to undo her spell on Wonder Woman, Batman does something he'd ''never'' normally do; sing in front of an audience.
* HiddenDepths: Who knew Batman was such a good singer?
* IGaveMyWord: Circe gives her word she would leave Hippolyta alone. That meant she could turn Wonder Woman (Hippolyta's daughter) into a pig, [[ExactWords as she never promised]] not to harm ''her''. She plays this straight later when she changes Wonder Woman back after Batman does as she requests [[ItAmusedMe (which is simply her idea of fun)]], despite her being clearly more powerful than Zatanna and Batman.
* ItsNotYouItsMyEnemies: Part of how Batman explains to Wonder Woman why they can't date. His enemies would try to get to him through her. Wonder Woman immediately crushes the head of a stone gargoyle.
-->'''Diana:''' Next?
* JerkWithAHeartOfGold: As usual, Batman. He is clearly worried about Wonder Woman, yet remains (or tries to) his cool, collected self.
* JustFriends: Zatanna lampshades the trope regarding herself and Bruce, despite previous ShipTease between the two. Her willingness to help Bruce restore Wonder Woman without any sign of jealousy (Zatanna points out that Batman/Wonder are more than just friends) shows [[AFriendInNeed Zatanna may be playing it straight]].
* JustInTime: Circe is convinced to dispel the curse she put on Wonder Woman ''just'' as Wonder Pig enters the machine that would've turned her into pork cutlets.
* LadyInRed: Circe sports a rather fetching red evening gown for her big musical number.
* LighterAndSofter: The episode is rather goofy and lighthearted by the show's usual standards.
* LongerThanLifeSentence: In return for her help in finding Circe, Medusa gets 300 years taken off her sentence in Tartarus, moving the projected date of her release up to 4010. She's [[FlatJoy not exactly thrilled]].
* LoopholeAbuse: The terms of Circe's parole from Tartarus prevent her from gunning for Hippolyta. However, the parole doesn't specify anything about Hippolyta's ''daughter''.
* TheMindIsAPlaythingOfTheBody: Wonder Pig, aside from being more scared of being turned into an English breakfast, acts basically like a normal pig.
* MsFanservice: Circe is an attractive immortal sorceress who not only sports a miniskirt in her regular costume, but also dons a skintight catsuit when posing as a robber, and then a red evening gown for her musical performance.
* MyEyesAreUpHere: When B'wana Beast arrives to help Batman and Zatanna, he first examines Zatanna from the feet up. The exchange provides the page quote.
-->'''B'wana Beast:''' ''(staring at her legs)'' B'wana Beast. How you doin'?\\
'''Zatanna:''' My ''legs'' are fine...as is the rest of me. ''(points to her face)'' Up here.
* NoodleIncident: Batman picked up the words to “Am I Blue” from staking out a singer the Penguin tried to kidnap.
* PowerfulAndHelpless: Circe cannot be defeated by Zatanna's magic or Batman's fighting skills, so he decides to negotiate by giving something up instead, and it works.
* ReactionShot: Just as Circe casts her spell on Wonder Woman, the camera pans to Batman's horrified reaction.
* ShipTease: In spades between Bruce and Diana. Batman all but confesses to Zatanna that he has feelings for Wonder Woman.
* ShoutOut:
** During Zatanna's magic show, the rabbit she plans to pull out of her hat is named "[[WesternAnimation/BugsBunny Bugs]]".
** (''Maybe...'') When Creator/LyndaCarter guest-starred on ''Series/TheMuppetShow'', it included a skit which featured Miss Piggy as "Wonder Pig", which Diana once gets called here.
** When Zatanna briefly crushes Circe with a levitated piano, the camera holds on a shot of her outstretched feet in red shoes, bringing to mind [[Film/TheWizardOfOz another witch crushed under a heavy object]].
** Circe's green outfit here closely resembles the outfit of Creator/MarvelComics' "[[ComicBook/TheEternals Sersi]]" (as designed by Creator/JackKirby) instead of anything that DC's Circe has worn.
** One of the abattoir workers that grabs Pig!Diana remarks, "[[Film/{{Babe}} That'll do, pig]]."
** According to Bruce Timm, one of the inspirations for the episode was the ''Buffy the Vampire Slayer'' episode "Bewitched, Bothered and Bewildered" (specifically the subplot of Buffy briefly getting turned into a rat). Timm thought the episode was going to end with the Buffy Rat kicking the ass of the cat that was trying to eat it, but of course it didn't. So Wonder Pig deflecting bullets with its bracelets was inspired by how Timm felt that ''Buffy'' episode's climax should have played out.
** Another inspiration was, well, ''Series/{{Bewitched}}'', and it's fairly obvious.
** Circe alludes to the [[Literature/BookOfExodus Biblical]] story of Moses and his brother Aaron confronting the Pharaoh's magicians after she turns her crowbar into a snake.
--->'''Circe:''' That trick always went over big in Egypt.
* TalkingIsAFreeAction: Zatanna averts this with quite a bit of prejudice towards Circe, who [[AddedAlliterativeAppeal tries to threaten the "trickster" three times]].
* ThisIsGonnaSuck: Batman shuts his eyes in defeat as Circe begins to spell out her demands from him...
* WhoDares: Circe tries to do this. Zatanna doesn't let her.
-->'''Circe:''' Insolent trickster! You dare to strike...''[hit with a chair]'' You dare to strike...''[hit with a table]'' You dare to strike...''[is covered with a tablecloth, yanks it off]'' QUIT IT! [[ThisIsGonnaSuck Oh no]]... ''[slammed by a piano]''
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