Her stars an actress.
Amy Lou Adams ( born August 20 , 1974 ) is an American actress and singer . Her (film) . The film follows Theodore Twombly ( Joaquin Phoenix ) , a man who develops a relationship with Samantha ( Scarlett Johansson ) , an intelligent computer operating system personified through a female voice . The film also stars Amy Adams , Rooney Mara , and Olivia Wilde .