Tommy Lee Jones may have the most eloquently ravaged face in current movies, and his journey in Paul Haggis’s “In the Valley of Elah” is a tough, mournful one. When he learns that his soldier son, just back from Iraq, has gone missing, he opens his own investigation. It’s not long before he confronts the worst: his son’s body, chopped into pieces, has been found in a field. Haggis’s first film since his Oscar-winning “Crash” unfolds as a murder mystery, but it’s one fraught with an angry, sorrowful political subtext and a tone that’s unvaryingly solemn. “In the Valley of Elah”—one of many American movies this fall that will weigh in on Iraq and Afghanistan—is far from the last word on the subject, but whatever its flaws, Haggis’s movie sends out an urgent distress signal that’s hard to ignore.