"Heart of Gold" is the seventeenth episode of the fourth season of the American fantasy drama series Once Upon a Time, which aired on April 12, 2015.
In this episode, Emma Swan must deal with the truth about her parents' past with Maleficent, while she tracks down the Author, whom she must find before Gold does.
Back in "Sherwood Forest many years ago," Robin Hood is at his bar, when the Sheriff of Nottingham shows up and threatens his nemesis over taxes and gives him just two days to get his money in order.
Robin then takes the guard’s clothing as a disguise and uses it to break into the Wicked Witch of the West’s palace, where he bottles some of the elixir, only to have Zelena catch him, immediately assuming he is there on Rumplestiltskin’s behalf.
Nine weeks earlier, after Robin kissed Regina before stepping over the magical boundary of Storybrooke (and nine weeks before the aforementioned phone call that Regina made) to leave with Marian and Roland, they have entered New York City, where Robin tells Marian that Regina gave her the keys to Neal/Baelfire’s apartment, but as they check for directions, a man on a bike snatches Marian’s purse and Robin tries to give chase, then steals a horse and goes after the thief; he runs the guy down and tackles him then stops himself, saying a thief who steals from those in need has no honor.
They then hear someone knocking on the door, and they see Gold there; he wants Robin and his family out of his son's apartment, saying that Regina told him about the Author and what will happen to her if her happy endings do not come true, but even as Robin refuses to give up the place Gold starts suffering chest pains and is taken to the hospital, where he is told that he had a heart attack.
Gold explains to Robin the only thing that can cure him now is the elixir of the wounded heart, which is actually being kept safe nearby at a place called "The Wizard of Oak."
David explains that they didn't understand what they did out of fear, but Emma snaps and says they’ve been lying to her and adds that she became the anointed savior because they destroyed someone else’s soul.
Amy Ratcliffe of IGN said of the episode, "The exploration of Robin Hood's origins slowed tonight's Once way down as everything about the trip to fairy tale land seemed like it was about forcing connections and parallels.
[3] Hilary Busis of Entertainment Weekly notes: "Like it or not, you’ve got to admit that Zelena’s return was the most exciting part of an episode that otherwise read as wheel-spinning.