Elizabeth Lail and Georgina Haig Elizabeth Lail and Georgina Haig

Beloved Frozen characters Anna (Elizabeth Lail, left) and Elsa (Georgina Haig) are joining ABC's Once Upon a Time.

The Frozen storyline, which picks up after the events of the movie, begins in the September 28 premiere. And Anna and Kristoff (Scott Michael Foster) are planning their wedding! Jokes executive producers Edward Kitsis and Adam Horowitz: "In case you are wondering, the happy couple is registered at Wandering Oaken's Trading Post and Sauna."

Subscribe to TV Guide Magazine now!