The book is about a group of servicemen sent on a 'Victory Tour' after returning from combat in Iraq.
The trip takes them to Texas, where they're hosted by the Dallas Cowboys at Thanksgiving time. Already cast are Garrett Hedlund, Steve Martin and Joe Alwyn, reported Deadline.
Lee begins shooting this month in Atlanta from a script by Oscar-winner Simon Beaufoy ('Slumdog Millionaire').
Platt, 21, will be playing Josh, who works for the Cowboys organisation and is the point person in charge of taking care of the Bravo Squad during its day at the football stadium.