Ariel (JoAnna Garcia), aka "The Little Mermaid," swam her way to 'Once Upon a Time' this week for a charming, if tragic, new episode. Staying true to form, 'OUAT' tweaked the classic Little Mermaid tale, adding darker shades to the story and setting the stage for a great surprise ending.

This episode began by telling Ariel's story in flashback. She saves Snow White from drowning and the two become fast friends in the Enchanted Forest. Ariel reveals to Snow that she once saved a prince named Eric from drowning in the sea, and she dreams of reuniting with him so they can get married and make little mermaid babies. Only trouble is, she's a mermaid, and he's a man who walks on two legs and ... well, you know the story. But as luck would have it, Eric is hosting a ball that very same night, and Ariel plans to attend with the hope of hooking up with Eric. She is granted legs by the sea goddess Ursula, but as mermaid mythology states, she must return to the sea within 12 hours, when her legs will disappear to be replaced by fins. Snow teaches Ariel the ways of the world and is determined to help her get her happily ever after.

Back in Neverland, Peter Pan is busy playing mind games with Rumpelstiltskin, who for some reason can't kill Pan without killing himself. Rumpel must choose between sacrificing his life to kill Pan and save Henry and Niel, or giving up and going back to Storybrooke to start a new life with Belle. Pan makes a pretty solid argument for convincing Rumpel to throw in the towel -- Neal doesn't trust him, and it's likely Henry doesn't either. And to make things worse, Pan makes some ominous references to Rumpel's father, further zapping his confidence and confusing him. It's a tough time to be the Dark One.

It's also a tough time to be the Evil Queen. In another part of the Neverland forest, Regina is playing Dumbledore to Emma's Harry Potter, but Emma proves to be a poor student when it comes to magic. Emma is able to start a fire, but it's clear that she's uncomfortable with the dark forces. In the same scene, Hook reveals to Snow and Charming that Neal is alive. Snow tells Emma, and they all decide to put the search for Henry on hold and find Neal first, which is a little odd. Regina is annoyed with Emma and the Charmings, and she refuses to look for Neal. She takes off on her own to find Henry.

In the flashback, Snow and Ariel arrive at Eric's ball. Ariel looks amazing in a tight dress and corset, and there's some funny stuff with her screwing up some social cues and falling on her face when she sees Eric. He asks her to dance, and he says he recognizes her from his dreams. Eric believes that Ursula granted him a vision of his true love, who looked just like Ariel. Eric is clearly smitten with Ariel, even though she's shy and nervous around him. She's worried he'll reject her after finding out she's a mermaid. These two star-crossed lovers come from two different worlds, and Eric would have to give up his life on land to be with Ariel. She can't bear to make him choose. But Eric isn't giving up on her. He tells her to meet him in the morning before he goes on a long sea voyage. If she shows up, they'll spend their lives together. If she doesn't, his heart will be broken. No pressure, Ariel!

Sadly, Ariel doesn't end up with Eric at the end of the episode. Before she can tell him the truth about her mermaid-ness, Regina shows up to spoil everyone's fun. In the silliest scene of the night, Regina poses as Ursula, eight slimy legs and all, and tricks Ariel into turning Snow White into a mermaid. In the second silliest scene of the night, Snow White flops around like a scared wet fish on a dock, frowning at her new fins and wondering where her legs went. When Ariel realizes Regina tricked her, she stabs her with a trident fork, breaking Regina's spell and returning Snow's legs. Ariel and Snow escape from Regina, and Snow encourages the little mermaid to meet up with Eric. But Ariel is still hesitant to reveal to Eric that she is a mermaid. When Snow finally convinces her that risking everything at a chance at true love is better than not trying, Ariel swims to Eric to tell him the truth. But Regina steals her voice, and Ariel loses her chance to speak to her prince. True love is postponed.

There's more tragedy to be had back in Neverland. Emma, Hook and crew are forced to reveal their deepest darkest secrets in order to rescue Neal from an enchanted cave. Hook admits that he can finally let go of his lost love because he is falling in love with Emma. Snow tells Charming she wants another baby, since they missed out on seeing Emma grow up. And Charming spoils the moment by revealing he can't leave Neverland without dying. Emma is forced to tell Neal that she still loves him, but she is afraid to face the pain of their past again and is unsure about their future. They rescue Neal, and Neal tells Emma he'll never stop fighting for her. Hook hears this and shrugs while Snow decides to shut Charming out. So now we've got a potentially juicy love triangle between Neal, Emma and Hook, and the show's uber couple, Snow and Charming, are on the outs.

Speaking of uber couples, Regina helps Rumpel see that his visions of Belle are the work of a shadow demon, and they soon ward off the shadow and come up with a plan to capture Pan. The Evil Queen and the Dark One join forces to give Pan "a fate worse than death," whatever that is. And the episode ends with a huge surprise -- Regina summons Ariel, restores her voice, and orders her to use her realm-hopping powers to retrieve a magic item from Rumpel's shop in Storybrooke. And there's a bonus for Ariel; Eric is in Storybrooke! Perhaps Ariel will get her happy ending after all.

In one of the most interesting moments of this week's episode, the real Ursula (composed of 100% CGI) appears a in a flashback and warns Regina never to impersonate her again. It makes you wonder if Ursula will appear next week, when Ariel grows a pair of legs and meets the good people of Storybrooke. Anyway, here's hoping she gets a second chance at a happy ending with Eric.