VIDEO: Sneak Peek - ONCE UPON A TIME's 'Lady of the Lake' Episode on ABC

On Sunday night's episode of the ABC drama ONCE UPON A TIME titled "Lady of the Lake" - Emma and Mary Margaret, with the aid of Mulan, Aurora and brave knight Lancelot, attempt to find a portal that will bring them back to Storybrooke. But a dark force threatens their safe return. And Henry tries to talk Jefferson into reuniting with his daughter. Meanwhile, back in the fairytale land that was, on the eve of meeting Prince Charming's mother, King George poisons Snow White, and the only antidote lies within the waters of the Lady of the Lake. The episode airs SUNDAY, OCTOBER 14 (8:00-9:00 p.m., ET) on the ABC Television Network. Get a sneak peek below!

"Once Upon a Time" stars Ginnifer Goodwin as Snow White/Mary Margaret, Jennifer Morrison as Emma Swan, Lana Parrilla as Evil Queen/Regina, Josh Dallas as Prince Charming/David, Emilie de Ravin as Belle, Jared S. Gilmore as Henry Mills, Meghan Ory as Red Riding Hood/Ruby, and Robert Carlyle as Rumplestiltskin/Mr. Gold.

Guest starring are Barbara Hershey as Cora, Alan Dale as King George, Sarah Bolger as Aurora, JAMIE CHUNG as Mulan, Sebastian Stan as Jefferson, Gabrielle Rose as Ruth, SINQUA WALLS as Lancelot and Alissa Skovbye as Paige.

"Lady of the Lake" was written by Andrew Chambliss & Ian Goldberg and directed by Milan Cheylov.