A U.S. Marine named Kyle Wincott is killed in Afghanistan, and his highly trained service dog, Max, suffers from trauma due to the incident. Max is unable to continue his military duties and is sent to the Wincott family back in Texas, where he forms a close bond with Kyle's teenage brother, Justin. Initially, Justin is reluctant to adopt Max, but he soon realizes that the dog needs him as much as he needs the dog. Through their growing friendship, Justin begins to uncover more about his brother's life and service, finding strength and a sense of responsibility.

As Justin and Max grow closer, they start to uncover suspicious activities involving members of the community and possibly Kyle's death. With the help of his friends, Carmen and Chuy, Justin navigates these mysteries while dealing with his strained family relationships and coming to terms with Kyle's loss. Their journey is one of building trust, understanding, and facing challenges head-on. From halfway through the story onwards, the stakes get higher, focusing on themes of loyalty, bravery, and the unbreakable bond between a boy and his dog.