Grace has joined the cast of "Breaking Dawn" as Irina, Deadline reports. The character is a vampire who mistakenly identifies Edward (Robert Pattinson) and Bella's (Kristen Stewart) child as an "immortal child" -- i.e., a human child who has been turned into a vampire, a practice outlawed by the Volturi.
Her claim becomes a source of major conflict in the novel, and we expect much the same from the film. "Breaking Dawn" is scheduled to begin filming later this fall, with part one due for release in November 2011 and the final installment a year later.
Bill Condon ("Dreamgirls," "Gods and Monsters") is directing "Breaking Dawn," and as she's done for the previous three "Twilight" movies, Melissa Rosenberg is writing the script.
Grace was a regular on "Lost" for its first two seasons, and she returned a couple of times after her character, Shannon Rutherford, was killed (including in May's series finale). She also starred with Liam Neeson in "Taken"; her other movie credits include "Knight and Day," "The Fog" and "The Jane Austen Book Club."