Laura Prepon Joins Castle as Nikki Heat

Castle's Kate Beckett (Stana Katic) will soon meet her cinematic doppelganger.

Laura Prepon (That '70s Show) has been cast as Natalie Gray, the actress who will portray Nikki Heat in the upcoming movie within the ABC show, a network rep confirms.

The film will be adapted from the fictional crime thrillers of Richard Castle (Nathan Fillion). As fans know, the character is heavily based on Beckett.

Castle dream casting: Who should play Castle and Beckett in the movie?

To get into character, Gray will travel to New York and shadow Castle and Beckett during a case, which revolves around the murder of a millionaire matchmaker.

Prepon is tentatively slated to first appear in the Jan. 3 episode, the same night as The Bachelor premiere.