AceShowbiz -

Kristen Stewart is in talks to become a part of Ang Lee's upcoming film "Billy Lynn's Long Halftime Walk". TheWrap reports that she will join Steve Martin, Garrett Hedlund and newcomer Joe Alwyn in the cast ensemble. The "Twilight" star will be playing the role of Kathryn, Billy's older sister in that movie. Alwyn is set to take the title role.

This movie is based on the bestselling novel by Ben Fountain which was adapted by Simon Beaufoy for the big screen. Beaufoy is known for winning an Oscar for his work on Danny Boyle's "Slumdog Millionaire".

Lee will be directing the film. He explained why he chose to work on this film, "The most important thing to me is storytelling and Billy Lynn's 'Long Halftime Walk' is a story that immediately gripped me. I look forward to starting the creative process with this extraordinary team of collaborators."

The movie centers on Billy Lynn, part of a unit called the Bravo Squad, fighting in Iraq. After Lynn and seven other surviving members return to the U.S., they are sent on a "Victory Tour" by the government. They are celebrated at the Dallas Cowboys' football stadium during the team's halftime show on Thanksgiving, before they are later sent back to Iraq.