Once Upon a Time season 3, episode 19, “A Curious Thing,” aired tonight and we have all the details in our full recap!

The battle between evil and wicked rages on in Storybrooke, but the key to saving the future once again falls on the shoulders of Henry. The heart of the truest believer must remember his past in order to save a future he does not quiet understand.

A Happy AnnouncementSnow and David gather the kingdom and prepare to announce their impending bundle of joy. Instead of casting hope out to the kingdom, Aurora and Phillip tell Snow that Zelena threatened their baby unless they informed her of Snow’s return to Storybrooke. Zelena appears and asks Snow to take care of the baby, she’ll be back to claim it.

Eight months later, Regina asks Snow how she knew to send her baby away the first time. Snow admits that Rumpelstiltskin gave her fair warning to prepare an escape for Emma. The assembled group, Belle, Robin Hood, Regina, Charming and Snow, decide that breaking into Rumple’s castle is their best option. Zelena is holding him captive inside, but it will take more than Regina’s magic to maneuver around the traps. A thief perhaps?

In a rush to the present, Robin and Regina continue to butt heads, but this time in a more passionate manner. Clearly in a smitten mood, Regina holds court with the assembled group to try to piece together why they needed to return to Storybrooke. Approaching the problem from another way, if they can determine the item Zelena loves the most and gave up to cast the curse, it will help them understand what it will take to defeat her. They need to get their memories back before Mary Margaret goes into labor.

Hook is also running out of time. Zelena captures him and issues the warning that she will soon take Henry’s life hostage unless Hook’s kiss removes her powers.

Book Smarts: One possible way to bring their memories back is to have the most powerful believer remember the life he lost to a memory spell. Without the storybook, however, their options are limited to a magic show until it shows up. Henry is becoming frustrated with his current prisoner lifestyle and tries to run away. Hook has a different plan in mind for the underage getaway car driver and with a lift of that eyebrow who would turn Killian down?

As Killian takes Henry to the dock and instructs him that he will set sail with Mr. Smee for New York, an army of flying monkeys has other plans for the heart of the truest believer.

During the lost year, the group head to Rumple’s castle, where the man who trades pinecones saves them from a few traps. Rumple, and Neal, are trapped in a cage sharing a body and muttering nonsense rhymes. Or so it would appear. Rumple mentions Glinda, the good witch of the South, banished to the Northern edge of the Dark Forest. Snow, Charming, and Regina set out after her with only the advice that the only the pure of heart may cross her doorway.

Snow and Charming make it through and learn from Glinda that there is no way to defeat Zelena without light magic. Emma, the product of true love, holds that power, however she resides in a world apart from them. It will take the curse to bring them back and retrieve Emma. However, who will sacrifice what they love the most to cast it? Glinda also informs them that the pendant is the source of Zelena’s magic.

To Kiss, or Not to Kiss:In the present, Snow is able to retrieve the storybook, which will hopefully refresh Henry’s memories. That is, if the flying monkeys across town have not already started that! Emma traces Henry’s cellphone to the harbor, where Hook, Regina, David, and Emma use magic, guns and swords to destroy mythical creatures before his eyes. Wishing she could take Henry back to New York without the memories of this world, Emma hands Henry the book and his memories return at once.

In the most heart-warming scene this season, Henry runs to Regina and calls her mom. But their reunion ends abruptly as Zelena takes Henry hostage. Zelena says she sent warning to Hook that this would happen, but Emma’s powers force her to burn at the touch of his skin.

In the past year, Charming allows Snow to take his heart and crush it in order to cast the curse. Before the curse has time to sweep over the land, Zelena sprinkles a bit of a memory spice in the mix. Even without their memories, they will still be able to figure out Zelena’s plan. Once Snow realizes that she will not remember sacrificing Charming, she decides to allow Regina to rip her heart in two and bring Charming back to life. With one heart, one true love will endure.

In the present, Hook tries to explain, but even his best excuses do not help him explain how he received the memo to retrieve Emma from New York. A flashback reveals that Neal’s love for Emma allowed him to separate himself from Rumple long enough to take Zelena’s memory potion to Hook’s ship.

Henry catches up Regina on the past year while everyone else explains to Emma that she is the only person who can stop Zelena. But the memories of the past year also mix with the present as Henry bids farewell to the father he remembers as a hero.

Mary Margaret’s contractions are not able to hold out any longer and the newest baby is on the way!

Watch Once Upon a Time season 3, episode 20, Sunday, May 4 at 8 p.m. ET on ABC