"Once Upon A Time" season 4 spoilers revealed the new casting call for an old and skilled knight, which could be a departure from the "Frozen" story arc. Is the show taking on a religious mythology?

Michael Ausiello dished out "Once Upon A Time" season 4 spoilers in response to a fan who asked for any other news outside of the "Frozen" story arc.

"For Season 4's fourth episode, the ABC series is casting the role of an elderly, grizzled and unflappable knight who for many, many years has dedicated himself to serving a righteous cause. Anyone else getting a Holy Grail vibe from this...?" he wrote.

Co-creator Adam Horowitz revealed "Once Upon A Time" season 4 spoilers on Twitter when he wrote that episode 1 will carry the title "A Tale of Two Sisters," which could refer to Queen Elsa and Princess Ana if the series will follow the "Frozen" story arc.

Then Adam Horowitz uploaded an image showing episode 2 with the title "White Out," along with the caption: "Here's another #OnceUponATime #titlespoiler Hope to see ya 9/28 for Season 4!"

Episode 3, meanwhile, will be called "Rocky Road," which could suggest a new challenge for the main characters. Could this be where the Ice Queen will make her appearance?

Those who watched "Frozen" may surmise that this would be the time when Queen Elsa in a moment of panic unleashed eternal winter in the kingdom. Earlier "Once Upon A Time" season 4 spoilers revealed that it would be "Ice vs. Ice" or Queen Elsa against the Ice Queen.

According to Inquistr, there's a theory that OUAT will tweak the story to make it appear that Queen Elsa's mother is still alive even if she presumably died in "Frozen." She could be saved by the mermaid Ariel when she saw the shipwreck.