With her mother, Cora, banished to another land and the spell book now in her hands (see Episode 202 - "We Are Both"), Regina has begun studying magic under Rumplestiltskin. The latest lesson is taking out a victim's heart so that you can control their will. But as Rumplestiltskin instructs Regina to tear out a horse's heart and crush it, she can't bring herself to do it. She can't help but remember how her mother tore out her lover, Daniel's, heart and killed him in the same way. She can't bear to use magic for evil the way her mother did. Rumplestiltskin feels like his time is being wasted, but Regina is eager to continue her training so that she can bring Daniel back from the dead. When she begs Rumple for more lessons, she crosses paths with Jefferson, a portal jumper who might know someone who can do exactly what she's looking for.
Word has begun to spread around town that the other worlds weren't actually destroyed by The Dark Curse. Someone who's particularly interested is Dr. Whale, who bursts into Regina's therapy session with Dr. Hopper and demands she send him back. She says she couldn't even if she wanted to, but clearly that's not good enough for the doctor. After therapy, Regina thinks she sees none other than her beloved Daniel staring at her on a street corner. Dazed, she looks for Dr. Whale in the hospital and finds him there, his arm torn off, moaning about unleashing a monster. Did he really bring Daniel back from the dead in Storybrooke?
In Fairy Tale Land, Jefferson takes Regina to meet a man from another land, a doctor, who we recognize as Dr. Whale. He claims to be able to revive the dead, but he needs an enchanted heart, like one plucked from a person's chest the way Rumplestiltskin showed Regina how to do, to complete his operation. Regina takes the doctor and Jefferson to her mother's vault which is full of throbbing, enchanted hearts stolen from poor souls all over the land. They choose one and the doctor sets to work. Regina had used a spell to preserve Daniel's body and thing appear to be going well. Lightning strikes the doctor's tent, but he soon emerges, sadly admitting that he failed. Regina, heartbroken, returns to Rumplestiltskin and eagerly plucks the heart from another student's chest, crushing it. She's ready for her next lesson.
Sometime later, we see Rumplestiltskin meeting with the doctor and Jefferson to conclude their business. The whole thing was a ruse to get Regina beyond her heartbreak so that she could continue her training. The doctor leaves for his world with an enchanted heart as payment, convinced his science is superior to magic and that his process for reviving the dead will indeed work to bring his brother back to life.
Regina discovers that Dr. Whale had stolen a heart from her own vault and used it to bring Daniel back to life, but Daniel seems to be insane and incredibly strong. Being a stable boy, he goes to the Storybrooke stables where Henry is meeting his new horse. David and Regina race there to find the boy being attacked. David wants to put Daniel down again, but Regina insists that her once-dead fiance will listen to her. At first he tries to strangle her, but slowly the real Daniel emerges, only to confess that he is in terrible pain and to beg that Regina let him go. Tearfully, she does, using magic to disintegrate him. For the second time, she has lost the love of her life.
In present day Fairy Tale Land, Emma, Mary Margaret, Mulan and Aurora return to the island encampment to find that it's been attacked by Cora. They find a lone survivor, none other than Captain Killian Jones aka Hook. Immediately Emma is suspicious and ties him to a tree. She whistles to summon some ogres and suggest he tell the truth if he wants to live. He is left with no choice but to reveal the ruse, that Cora wanted him to get close to them so he could find out more about Storybrooke. He offers to help them get there the same way he planned to help Cora, so long as he gets revenge on Rumplestiltskin. There doesn't seem to be a lot of objections from any of the four Princesses.
Then we flash not to Fairy Tale Land, but to another world, where the doctor and his assistant work in a gloomy castle laboratory. As the doctor places the enchanted heart into the body on the table before him, lightning strikes and the creature's stitched-together hand begins to move. It's alive! And we realize this is Dr. Victor Frankenstein who will somehow be transported to Storybrooke as Dr. Whale! And in Storybrooke, Dr. Whale drags his severed arm to Mr. Gold's pawnshop for help. The price, this time, is relatively cheap. Rumplestiltskin merely asks that he admit he needs magic. When the doctor does, his arm magically grows back. It seems the rivalry between science and magic isn't quite done yet.