Kyle (Robbie Amell) is a Marine Corps member, and Max, a loyal military dog, is his partner and comrade-in-arms. The two shuttled between gunfire and rain of bullets, experienced many life-and-death critical moments, and forged a deep friendship. In the end, Kyle died on the battlefield, and the heartbroken Max suffered from post-traumatic stress disorder. Max, who was unable to fight and refused to recognize his new owner, had to leave the army. Kyle's family adopted Max, and Kyle's younger brother Justin (Josh Wiggins) loved him very much. This is a loyal dog with a story. Under the gentle protection of Kyle's family, Max's mental illness gradually recovered and regained his vitality. Just as the family was enjoying themselves, a man named Taylor (Luke Kleintank) appeared in front of Max, claiming to be Kyle's former comrade-in-arms.