Once Upon a Time fans, listen here! If the speculation for Elsa and Anna’s back story on the show’s incorporation of Frozen was not enough, here is another bit of casting news and the premiere title!

Take a deep breath and pop in that Frozen DVD, today Once Upon a Time creators add another cast mate, Elizabeth Mitchell, to the season 4 ensemble.

Viewers may recognize Mitchell from her roles as Juliet Burke on Lost and, more notably, as Mrs. Claus in The Santa Clause 2 and The Santa Clause 3.

The creators of Once Upon a Time sure have a soft spot for veterans of Lost. Mitchell joins Emilie de Ravin, Jorge Garcia, Alan Dale, Eric Lange, and Rebecca Mader. Naveen Andrews has also made an appearance on the show’s spin-off Once Upon a Time in Wonderland.

Without much to go on, the character is speculated to fall on the evil end of the spectrum. Perhaps the answer to her role lies in the depths of the Hans Christian Andersen tale of The Snow Queen. As previously reported, the Frozen story line will pick up after the events of the movie. Perhaps Mitchell’s character will provide the answer to why Elsa ended up in Rumpelstiltskin’s vault.

Mitchell will join Scott Michael Foster (Kristoff) Elizabeth Lail (Anna) and Georgina Haig (Elsa) in both the Storybrooke and Arendell worlds. No word if fans can expect a CGI rendering of Olaf. (We can keep wishing, though!)

Creator Adam Horowitz took to Twitter yesterday to reveal the title of the premiere episode:

“A Tale of Two Sisters.” Are you surprised?

Thanks, EW.

For more ‘Once Upon a Time’ casting news check out these articles

• Once Upon a Time rounds out Frozen casting with Elsa

• Once Upon a Time finds Anna and Kristoff for season 4

Once Upon a Time returns with all new episodes this fall

Who purpose do you think Mitchell will serve on ‘Once Upon a Time?’