Jones plays a retired army sergeant named Hank Deerfield from Munro, Tenn., whose glory days are far behind him, as evidenced by his current job laying gravel. Deerfield and his wife Joan (Susan Sarandon) live a fairly routine life until the day he gets a phone call that changes their lives forever. The Army informs Deerfield that his son Mike (Jonathan Tucker) is missing and is assumed to be AWOL shortly after his return from Iraq to Fort Rudd, N.M. Refusing to believe that his son can be so careless, Deerfield decides to take matters into his own hands.
Leaving behind his oblivious wife, Deerfield sets off to the military base. En route to the base, Deerfield spots an American flag hanging upside down in front of a school. While he uprights the flag, Deerfield tells the school's caretaker that an inverted flag is an international distress signal that can cause chaos and concern throughout the country. This ominous incident foreshadows the sinister events to come.
Deerfield does everything he can to find out what has happened to his son. However, this isn't an easy task because no one is telling the truth about the day his son disappeared. Despite the Army's prohibition on removing items from his son's room, Deerfield craftily snatches his son's phone in the hopes that its media messages will provide the answers he is looking for.
When a brutally mutilated body is found in the middle of a field next to the base, Charlize Theron appears, giving a dominant performance as Detective Emily Sanders. The Army believes the corpse is the remains of Deerfield's son, Mike. This spurs Deerfield to embark on an investigation of his son's murder that rivals today's most popular crime shows. Sanders and Deerfield team up in an effort to solve the mysterious murder of his son.
Once he has confirmed that the corpse is really the body of his son, Deerfield finally tells his wife that her second son has died while serving in the military. We learn that their older son David was killed in a helicopter crash and that his death had devastated the Deerfield family. Now that her second son is dead, Joan resents her husband for making their sons feel as if they had no choice but to enter the military. Sarandon gives a subtle, but superb, performance as a grieving mother who must deal with the deaths of her two sons and the tensions in her relationship with her uncommunicative husband.
In addition to the main characters, there are numerous supporting roles of Army personnel and police detectives played by a host of talented actors including James Franco, Josh Brolin and Jason Patric. They contribute to the film's mystery and its various plot twists with convincing, passionate portrayals of their characters.
Throughout Deerfield's and Sanders' investigation, we get a glimpse into the situation in Iraq. It is obvious that the soldiers who have returned from their service in the war have been traumatized by their experiences abroad. Despite the film's explicit message that being in Iraq can seriously change a person, "In the Valley of Elah" is not an anti-war movie that advocates for peace and criticizes the U.S. government.
When Deerfield tells a bedtime story to Sanders' son, we finally learn that the Valley of Elah is where the famous biblical battle between David and Goliath took place. The story is one in which David, the underdog, triumphs over Goliath, the Philistine giant, despite overwhelming odds. In a way, Deerfield is the regular guy taking on his own terrifying giant as he overcomes obstacles to uncover the truth behind his son's death. Like David, Deerfield never allows his fear to stop him as he avenges his son's murder. He knows that to do otherwise would have prevented him from accomplishing anything.