Max, a military dog, serves on the frontlines in Afghanistan alongside his handler, U.S. Marine Kyle Wincott. When things go wrong, Kyle is mortally wounded and Max is unable to remain in service. Shipped stateside, the only human he is willing to connect with is Kyle's teenage brother, Justin, who isn't interested in taking care of Max. But Max may be Justin's only chance to discover what really happened to his brother, and Justin begins to appreciate his canine companion. Justin's growing trust in Max helps the four-legged veteran revert back to his heroic self, and as the pair race to unravel the mystery, they find more excitement and danger than they bargained for. But they each might also find an unlikely new best friend in each other.