Let's start with present day Storybrooke.
Henry and Charming are working their way through "Project Scorpian/Viper", Henry's cute codename for "Let's save mom and grandmom". Henry's pissed that Charming not only found the Mad Hatter, but let'em run off and never said anything to Henry (Though in Charming's defense, Henry had gotten swooped up by Regina at the time, so he was fairly distracted). Charming tells Henry it would be safer if Henry just backed off and let him handle the heavy stuff. Not taking that lightly at all, Henry takes it upon himself to also find the Mad Hatter and ask him almost the same questions Charming did. He finds him at the docks, and asks him why he hasn't gone to see his daughter. We find out the Hatter is plagued by this idea that his daughter would hate him for leaving her. But of course we get a super sweet moment when he does see her and they're reunited. D'aww...
Henry's next plan of attack is to steal Regina's keys and look for her vault. When he finds it, he opens a box and is about to be attacked by these crazy magical snakes when Charming comes in from behind him, closes the box and the two have a heart to heart. Charming agrees to let Henry in and work with him, and the two are left practicing sword fighting (with wooden swords). But who's watching in the distance? The old king, who spent his time in Fairyland keeping Snow and Charming apart.
Speaking of the Old King, let's jump back to past Fairyland.
Snow and Charming are on the run from the king. When they take out another ambush, they decide to split up and meet at Charming's mom's house. Snow gets caught by this guy named Lancelot, and taken to the king. The king poisons her and makes her unable to have kids, because that's the pain he wants Charming to feel. Lancelot doesn't like this one bit, and ends up helping Snow back to Charming's mom's house, where the kings men have just left, leaving Charming winded and his mother with an arrow in her chest. Charming insists they can get to the lake and the water will heal her. On the journey there, Snow and Momma get real close, and Snow tells her about being poisoned, though she can't bring herself to tell Charming.
When they get to the lake, it's all kinds of dried up. "I guess that's because I killed the Lady of the Lake" said Charming. Gee, really? Think that did it? They manage to find this seashell that has one mouthful of water left in it. Charming gives it to his mother, who this whole time since learning about Snow has been begging her to drink it instead. Snow refuses, and we see Momma take the mouthful. When it doesn't heal her, Snow and Charming ask Lancelot to perform a wedding ceremony for them so Momma can see her son marry before she dies. During the ceremony, Charming and Snow drink from this wedding chalice, and right before Momma dies, Snow realizes that Momma got Lancelot to change out the water, so Snow did ultimately drink that magic lake water.
And finally, speaking of Lancelot, let's jump over to present day Fairyland.
Snow and Emma are hanging with Cora in this pit. Snow is losing her shit over being near Cora, and Emma's having a hard time understanding why she can't trust this sweet older lady. Emma and Snow and called up from the Pit and meet with the group's leader....Lancelot! He tells Snow he's sorry for them being put there, that he didn't realize who Mulan had caught. Snow tells him she might know a way to get back, that the wardrobe they sent baby Emma over in might still exist. With Mulan in tow, Emma and Snow go off to find it. Aurora, still hurting over Phillip, tries to come after Snow. Mulan ends that, but not before Emma fires a gun and attracts all kinds of creature attention. Emma's clearly out of her element and doesn't like it one bit.
They get to the castle and Emma and Snow are each dealing with swirling emotions at seeing Emma's baby room. Just as they see the wardrobe, Lancelot appears. Saying he heard about the ogre attack, he claims to want to make sure they make it back safe. Snow isn't buying it, and Lancelot turns into Cora. Cora laughs, saying she killed Lancelot eons ago, but no one would follow her unless she made them think she was Lance. A bit of a scuffle happens, Emma lights the wardrobe on fire, and Cora puffs away in purple smoke. Emma and Snow come to this sort of mutual understanding about each other, and build on their new mother/daughter relationship.
And as they leave, Cora comes back into the empty room, and is eyeing that wardrobe up real good...