WITH MARY MARGARET IN LABOR, THE RESIDENTS OF STORYBROOKE GO ON HIGH ALERT TO ENSURE THAT ZELENA DOESN'T TRY TO STEAL HER NEWBORN BABY, AND IN THE LAND OF OZ OF THE PAST, A YOUNG GIRL FROM KANSAS THREATENS TO BE ZELENA'S UNDOING, ON ABC'S "ONCE UPON A TIME"

"Kansas" - With Mary Margaret in labor and due to give birth at any moment, the residents of Storybrooke go on high alert in an attempt to ensure that Zelena doesn't try to steal her newborn baby for use in her ultimate game plan to turn back time and change her destiny -- while obliterating Regina's existence. Meanwhile, in the land of Oz of the past, Glinda tries to convince Zelena to fight her evil tendencies and join her and her sister witches as a protector of Oz. But the appearance of a young girl from Kansas could turn out to be her undoing, on "Once Upon a Time," SUNDAY, MAY 4 (8:00-9:00 p.m., ET) on the ABC Television Network.

"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, Emilie de Ravin as Belle, Colin O'Donoghue as Hook, Michael Raymond-James as Baelfire/Neal Cassidy, Jared S. Gilmore as Henry Mills and Robert Carlyle as Rumplestiltskin/Mr. Gold.

Guest starring are Lee Arenberg as Leroy/Grumpy, David Anders as Dr. Whale, Raphael Sbarge as Archie Hopper/Jiminy Cricket, Rebecca Mader as Zelena, Gabe Khouth as Mr. Clark/Sneezy, Sunny Mabrey as Glinda, Sean Maguire as Robin Hood, Jason Burkart as Little John, Sharon Taylor as Witch of East, Karen Holness as Witch of North and Matreya Scarrwener as Dorothy.

"Kansas" was written by Andrew Chambliss & Kalinda Vazquez and directed by Gwyneth Horder-Payton.

"Once Upon a Time" is broadcast in 720 Progressive (720P), ABC's selected HDTV format with a 5.1 channel surround sound. This program carries a TV-PG,L,V parental guideline.

For more information on "Once Upon a Time," visit ABC.com/Once