Actors Ginnifer Goodwin And Josh Dallas, Right, From The TV series 'Once Upon A Time.'
Actors Ginnifer Goodwin and Josh Dallas (R) from the TV series "Once Upon A Time&" arrive at the 15th Annual Costume Designers Guild Awards in Beverly Hills February 19, 2013. Reuters

"Once Upon A Time" Season 3, Episode 4, titled "The Apprentice," airs Sunday, Oct. 19, on ABC. This new episode continues to unravel the story between Queen Elsa of Disney's "Frozen" and the Enchanted Forest "Snow Queen."

Spoiler alert: This update contains Once Upon A Time Season 4 spoilers. Read at your own risk if you have not watched the previous episodes.

The Snow Queen is Elsa's aunt. At least that is what she tells Anna's sister in Once Upon A Time Season 4, Episode 3. Toward the end of the episode, Rumplestiltskin shows and offers the Snow Queen his help. She says she is not ready to make a deal with him just yet.

The former evil queen Regina reveals to Henry his plan to look for the storybook author and ask for a happy ending. Henry approves of the plan, to Regina's surprise. This is the other mystery in Once Upon A Time Season 4.

The main mystery involves the Emma-Snow Queen connection, the real Elsa-Snow Queen history, the message from parents of Elsa and Anna, the present whereabouts of Anna, and her deal with Rumplestiltskin. In Once Upon A Time Season 4, Episode 4, it is revealed that in the past, Anna agreed to help Rumple on a quest.

In another side mystery, the Snow Queen tells Elsa in Once Upon A Time Season 4, Episode 3, that her dark spell on Marian (Robin Hood's wife) is meant to teach a lesson to the Arendelle queen. It remains to be seen, however, whether Marian has been a deliberate choice to get Regina involved.

Still in OUAT 4x3, Regina rips out Marian's heart just in time, so Robin Hood's wife could stay alive while they are figuring out how to break the frozen spell cast on her. Robin Hood suspects that true love's kiss has failed to work because he does love Regina.

Meanwhile, Emma Swan tells Captain Hook how much he means to her, in a rare act of opening up about her feelings. "Captain Swan" shippers are hopeful these two would get their happy ending in OUAT.

Once Upon A Time Season 4 airs Sundays on ABC. Josh Dallas and Ginnifer Goodwin, who play Prince Charming and Snow White, respectively, are also lead stars in the show.

Related TV Stories, Episode Guides and Spoilers

'Once Upon A Time' Season 4, Episode 3 Spoilers: Queen Elsa Of 'Frozen' Meets The 'Snow Queen' In ABC Promo Video; Emma Swan Faces Magic Test [WATCH]

'Revenge' Season 4, Episode 3 Spoilers, Speculations: Victoria Grayson vs David Clarke vs Emily Thorne In Dark Twists [Watch Promo Video]