VIDEO: Sneak Peek - 'Welcome to Storybrooke' on ONCE UPON A TIME

On the upcoming episode of ABC's ONCE UPON A TIME titled "Welcome to Storybrooke" - Emma, David and Mr. Gold must protect Mary Margaret against Regina, who is out for revenge and has made it her mission to kill Mary; and Henry, fed up with all of the feuding, devises a plan to put an end to magic.

Meanwhile, Regina discovers that a father and son have somehow found their way into her allegedly undetectable town as she and the fairytale characters deal with the effects of the newly cast curse 28 years prior. The episode airs SUNDAY, MARCH 17 (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, Colin O'Donoghue as Hook, Jared S. Gilmore as Henry Mills, Meghan Ory as Red Riding Hood/Ruby, and Robert Carlyle as Rumplestiltskin/Mr. Gold.

Guest starring are Raphael Sbarge as Archie Hopper/Jiminy Cricket, Jamie Dornan as Sheriff Graham/Huntsman, Tony Amendola as Geppetto/Marco, Michael Raymond-James as Neal Cassidy, Beverley Elliott as Granny, Jarod Joseph Billy, Ethan Embry as Greg Mendell, Benjamin Stockham as Owen Flynn, John Pyper-Ferguson as Kurt Flynn and Steve Makaj as captain.

"Welcome to Storybrooke" was written by Ian Goldberg & Andrew Chambliss and directed by Dave Barrett.