The story follows two drug kingpins living in Laguna Beach who are forced to work for a Mexican cartel after their free-spirited friend O is kidnapped.
Oliver Stone has been conducting readings for O, the last big role yet to be cast.
There was interest in Jennifer Lawrence, but her recent commitment to Lionsgate's The Hunger Games forced her to pass on the role. Teresa Palmer, Blake Lively and Olivia Wilde are rumored to read for the character.
Savages will start production in June.