Born on the Fourth of July begins with Kovic's childhood in a Long Island suburb of New York. Young Kovic and his friends pretend they are soldiers in the woods near his home. He spends golden summers playing baseball, eagerly awaiting the town’s Fourth of July parade, which is also his birthday. The idyllic setting is exaggerated to show the contrast between Kovic's childhood and his life during and after the Vietnam War. Stone throws in just a few blemishes to hint that life wasn't all peaches and cream. As Kovic sits on his father's shoulders during the parade he watches one of the marching veterans (the real Ron Kovic in a cameo) wince at the sound of firecrackers popping. Kovic also faces a lot of scrutiny from his overbearing mother (Caroline Kava) who expects perfection from her children. She tells Kovic that she will “love him anyway” even if he loses his wrestling match, but that he had better win regardless. She tells him that God will punish him after she finds a Playboy magazine hidden in his room.
Kovic's mother also encourages him to go fight the war in Vietnam. She says it is his duty to fight the spread of communism. Kovic and a few of his friends are more than ready to head overseas and live out their childhood war fantasies. They’ve heard the war will be quick and easy, even fearing it will be over before they finish boot camp. Flash forward several years and Kovic is serving his second tour of duty in Vietnam. He witnesses atrocities beyond the scope of his imagination. He is thrust into situations impossible to rationalize. Kovic is wounded during battled resulting in paralysis from his mid-chest down. He spends months in a VA hospital before finally returning home.
Despite his injury and paralysis he remains as determined as he ever was. The scenes in the VA hospital are truly horrific. They are almost more terrible than many of the war scenes. Although Kovic is determined to recover, he must reluctantly accept that he will never walk again. Upon returning home to his parents he is eager to be a part of the Fourth of July parade. However, the parade is not the same as he remembered it. The crowd is mixed with war protesters who taunt him. He is confronted with hatred toward the government and military he has never faced, or even thought about, before. He spirals out of control when he begins to feel he has no purpose. It is not until he gets involved with political activism that he experiences a new self-discovery.