Over the last year, Chastain has emerged as one of the busiest actresses in any genre.  She's currently starring as a younger version of Helen Mirren's character in The Debt and plays a part in the surprise hit ensemble The Help.  Earlier this summer she starred alongside Brad Pitt in Terrence Malick's ethereal The Tree of Life, and will also appear in the director's as-yet untitled next project. 

Take Shelter, in which she stars with Michael Shannon, just played Fantastic Fest and has been exceedingly well received on the festival circuit.  Later this year, she'll appear in Ralph Fiennes' directorial debut Coriolanus and Texas Killing Fields. Finally, next year she'll show up with Gary Oldman, Tom Hardy, and Shia LaBeouf in John Hillcoat's The Wettest Country in the World.

Horizons is a would-be blockbuster set in a post-alien invasion future where the surface of Earth has been irradiated, forcing what remains of humanity to live in the clouds.  Cruise plays Jack, a soldier assigned to repair the drones that scour Earth's surface for hostile aliens.  One day, while on a routine repair mission, he encounters a crash-landing that changes everything.  The two major females are Julia, Jack's pre-invasion fiancee, and Victoria, his eyes in the sky who monitors him on repair missions.

A month ago, Chastain was included on a shortlist of actresses testing for Horizons.  That list also included Olivia Wilde, Brit Marling, Olga Kurylenko, and Noomi Rapace.  We don't yet know whether Chastain is playing Victoria or Julia, and it stands to reason that these actresses could very well still be up for the other part. 

The film is based on a comic book titled Oblivion by Andree Wallin and Joseph Kosinski, with a screenplay by Karl Gajdusek, William Monahan, and Michael Arndt.  Universal is looking to start production this winter, presumably after Cruise finishes up Christopher McQuarrie's One Shot. 

Horizons is set to arrive in theaters on July 19, 2013.