“In the Valley of Elah“–Paul Haggis’s follow-up to his Oscar-winning “Crash”–starts out as a mystery about a soldier who disappears soon after returning home from Iraq. But it soon becomes something more: a full-scale exploration of America’s involvement in Iraq and the moral ramifications of the war. Starring Tommy Lee Jones and Susan Sarandon, the film opens in limited release this weekend, and in wide release on Sept. 21. Watch a clip here: