Newly separated from his wife Catherine, Theodore works for a company that composes love letters for those who lack the creativity to pen their own. Growing more and more isolated from the outside world, his curiosity is piqued by a campaign advertising the latest artificially intelligent operating system. When he is first introduced to his new technological assistant Samantha he is surprised by her ever-growing emotionality and fresh way of looking at the world. As time passes, Theodore finds himself connecting with Samantha in ways he could never have imagined, his perfect partner in a world that seems to have moved on without him. A beautifully shot and thoughtfully observed observation on loneliness and the need for love, with a moving, heart worn central performance from Phoenix.