Max, a precision-trained military dog, serves on the frontlines in Afghanistan alongside his handler, U.S. Marine Kyle Wincott. But when things go terribly wrong on maneuvers, Kyle is mortally wounded and Max, traumatized by the loss of his best friend, is unable to remain in service. Shipped stateside, the only human he seems willing to connect with is Kyle's teenage brother, Justin. Justin's growing trust in Max helps the four-legged veteran revert back to his heroic self, and as the pair race against time to unravel the mystery behind Kyle's death, they find more excitement-and danger-than they bargained for. But they each might also find an unlikely new best friend... in each other.