ONCE UPON A TIME: ‘Kansas’ Photo Preview

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. (ABC/Katie Yu)JOSH DALLAS, GINNIFER GOODWIN