The story flashes back and forth between a squad of eight US soldiers, the titular Billy Lynn (British newcomer Joe Alwyn) among them, sheepishly taking the limelight – and the hero worship – of Cowboys Stadium during an NFL game at which they are guests of honour, and their traumatic tour in Iraq. If and when she signs up, Stewart will play Lynn's big sister Kathryn.
Simon Beaufoy (Slumdog Millionaire) has adapted the novel and will be juicing it for satirical, peppery comment on America's relationship with its foreign wars and its own servicemen.
Shooting is due to kick off later this month, with Atlanta standing in for Dallas.
Stewart, like her fellow Twilight series co-star Robert Pattinson, have been making some canny choices since that franchise wrapped up and this looks like another. Stewart will next be seen in Drake Doremus' (Like Crazy) Equals and Olivier Assayas' (Summer Hours) Clouds Of Sils Maria, with a spot also secured in Woody Allen's (Midnight In Paris) next project.