‘Once Upon A Time’s’ Robert Carlyle and Emilie De Ravin muse Elsa’s origins

SAN DIEGO – As 'Once Upon A Time' gears up for its fourth season, the cast made an appearance at San Diego Comic-Con to tease the future of Storybrooke's citizens. Newlyweds Rumpelstiltskin (Robert Carlyle) and Belle (Emilie de Ravin) joked about their fallout when season three secrets are inevitably revealed.

“I could just take them off [Belle's stilettos] and use them as weapons,” de Ravin said.

But when it comes to the biggest secret – the arrival of “Frozen's” Elsa – even the stars are in the dark. Carlyle admitted Rumple's history with Arendelle's queen is a mystery.

“There's a lot of things in that vault I had no idea about. I genuinely don't know. Obviously he knows her, she knows him […] but I don't yet know what that relationship is,” he said.

On the subject of Rumpelstiltskin's tendency to keep volatile things under lock and key, de Ravin has a plan to keep Belle out of its gloomy recesses. 

“You better not throw me in that vault next…the heels will come off.”

“Once Upon A Time” returns to ABC on September 28.