More of Regina's (Lana Parrilla) complicated past with her mother Cora (Barbara Hershey) will be revealed in the next episode of ABC's Once Upon a Time.

Lana Parrilla Teases Return Of 'Evil Queen' on 'Once Upon a Time'

ABC has released a plot synopsis for the next episode of Once Upon a Time, which is titled Mother. As suggested from the title, the episode deals with motherly relationships both in the present and the past.

The present day storyline revolves around Lily (Agnes Bruckner) reuniting with her mother Maleficent (Kristin Bauer van Straten) while the flashback delves more into Regina and Cora.

Snow Severely Injured In Promo For Next Episode of 'Once Upon a Time'

"Emma [Jennifer Morrison] returns to Storybrooke to reunite Lily with Maleficent while Regina and Robin [Sean Maguire] struggle to cope with the implications of Zelena's [Rebecca Mader] pregnancy." the synopsis reads. "In a Fairy Tale Land flashback, Cora returns from Wonderland to beg Regina's forgiveness on the anniversary of Daniel's murder. Cora vows to help her daughter find true love, but Regina remains suspicious of her mother's intentions."

Meanwhile, Mr. Gold (Robert Carlyle) will have his own complications as his health declines even more.

"When Gold's health takes a turn for the worse, Isaac [Patrick Fischler] looks to a new ally for help procuring the magic ink he needs to re-write history," the synopsis reads.

The episode is written by Jane Espenson with direction by Ron Underwood. It will air on Sunday, May 3 in the regular OUAT timeslot.

Once Upon a Time airs Sundays at 8 p.m. ET/PT on ABC.

Watch the promo for the next episode of Once Upon a Time here:

Tags: Once Upon A Time television ABC