VIDEO: Sneak Peek - Mulan & Red Riding Hood to the Rescue on ONCE UPON A TIME

On the next episode of ABC's ONCE UPON A TIME titled "Ruby Slippers", in flashbacks, Ruby and Mulan find themselves in Oz, where they meet Dorothy. After the three witness Zelena's return to Oz, they look for a way to defeat her once and for all.

However, Dorothy mysteriously disappears, and Ruby's search for her new friend lands her in the Underworld. Reunited with the heroes, Ruby teams up with Emma, Regina and Snow to continue looking for Dorothy. Meanwhile, Snow and David struggle with not being able to be with their son, Neal, and devise a plan so that one of them can escape the Underworld

The episode airs Sunday, April 17th on ABC. 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 the Evil Queen/Regina, Josh Dallas as Prince Charming/David Nolan, Emilie de Ravin as Belle, Colin O'Donoghue as Hook, Jared S. Gilmore as Henry, Michael Socha as Will Scarlet and Robert Carlyle as Rumplestiltskin/Mr. Gold.