First, at the funeral for Kyle Wincott, Justin's older brother. Justin met Max in person, to see the dog just as heartbroken as Justin.
Next, after Justin meets his best friend's cousin, Carmen, she wants to help Justin train Max to get used to other people and be better to Justin.
Then, Justin and Max find out about his secret/illegal business with some really bad people from mexico. He was selling the guns similar to ones Kyle had gotten shot with in battle.
After that, Justin's dad came to tell justin the truth about how he got injured in battle. He got shot down in a friendly fire and someone told stories that he was shot in a full on attack and he embraced the lye.
Finally, Tyler was put in jail for his little business and for threatening the whole Wincotts family. Then Chuy, Carmen, Mr/Mrs. Wincott had a big end of summer dinner together. As for justin and Max they had friendship that would last them forever.
The theme of the book MAX is to put family first because in the story Justin was looking out for his dad and Max when both of them were in trouble.