'Her' Trailer: Spike Jonze Wonders What Makes Lovers Click

The new film from Spike Jonze is Her, which delves into the strangeness of modern relationships through an unusual device: Joaquin Phoenix plays a man who falls in love with a piece of software, appealingly voiced by Scarlett Johansson.

Set in a slightly sci-fi near-future Los Angeles, the story features Phoenix interacting with Johansson in voice only, through an earpiece that allows him to stay in constant contact with the operating system of his dreams. This is no glib gag laughing at the idea of a man/machine romance, however, but an earnest inquiry into what makes relationships tick.

There's a new trailer out today, which you can see below.

Her opens in some markets on December 18; it goes into wider release in January.

Set in Los Angeles, slightly in the future, "her" follows Theodore Twombly, a complex, soulful man who makes his living writing touching, personal letters for other people. Heartbroken after the end of a long relationship, he becomes intrigued with a new, advanced operating system, which promises to be an intuitive entity in its own right, individual to each user. Upon initiating it, he is delighted to meet "Samantha," a bright, female voice, who is insightful, sensitive and surprisingly funny. As her needs and desires grow, in tandem with his own, their friendship deepens into an eventual love for each other. From the unique perspective of Oscar-nominated filmmaker Spike Jonze comes an original love story that explores the evolving nature—and the risks—of intimacy in the modern world. In select theaters November 20, 2013.