"Birds of Prey" is close to completing its flock.

The Harley Quinn spinoff starring Margot Robbie has found an actress to play Cassandra Cain. Variety reports the newcomer Ella Jay Basco is in talks for the last major unfilled role.

She'll join Mary Elizabeth Winstead as Huntress, Jurnee Smollett-Bell as Black Canary. Rosie Perez is playing Gotham City police detective Renee Montoya, with Ewan McGregor on board as the villain Black Mask.

In the DC Comics, Cassandra is the daughter of assassins who was conditioned from childhood to follow in their footsteps. She grows up to be an expert martial artist, though she is mute, illiterate, and has no social skills. She eventually becomes one of the many Batgirls in the DC universe.

In the movie, Harley Quinn, Huntress, and Black Canary team up to protect Cassandra when she comes across a diamond belonging to the Black Mask.

This is Basco's first big role; she has appeared as a guest star on "Grey's Anatomy" and "Veep."

"Birds of Prey" is slated to open in theaters February 7, 2020.