O'Brien visits Jimmy Cross and asks if he can write about Martha and Ted Lavender and Vietnam. Cross says yes.
Fresh out of college and about to head to Harvard for grad school, O'Brien is drafted into the army. He contemplates running away to Canada, but just can't go through with it.
In Vietnam, O'Brien has to throw down pieces of Curt Lemon's body from a tree.
He kills an anonymous young man on a trail outside My Khe and can't stop staring at the body.
O'Brien's daughter, Kathleen, asks if he's ever killed someone, and he tells her no.
O'Brien publishes one book, If I Die in a Combat Zone, and is working on another, Going After Cacciato, when Norman Bowker writes to O'Brien and asks him to write about how Bowker failed Kiowa in the sewage field.
O'Brien publishes a version of the story that leaves out Bowker, Kiowa, and the sewage field. Bowker comments bitterly on this, then hangs himself. Ten years later, O'Brien fixes the story and publishes it as part of this collection, "Speaking of Courage."
When the platoon is camped in a latrine and it's raining and flooding like crazy, he switches on his flashlight to show Kiowa a picture of his girlfriend, and the platoon comes under attack. Kiowa gets hit, then drowns in the muck, and O'Brien blames himself.
O'Brien takes Kathleen on a trip back to Vietnam, where he visits the field Kiowa died in and sinks Kiowa's moccasins into the river.
He's shot once, in the side, and Rat Kiley takes good care of him. He's flown to the hospital and returns to the platoon 26 days later.
Not too long after that, he's shot again, this time in the butt. The new medic, Bobby Jorgenson, takes terrible care of him, and not only does O'Brien nearly die of shock, he also gets gangrene of the butt.
After his injury, O'Brien is taken to the rear (pun intended), where he works in a battalion supply section.
When his old platoon comes to the section for a break, he plays an elaborate prank on Bobby Jorgenson in revenge for nearly causing his death from the butt wound. The prank isn't a total failure, but because O'Brien involves Azar, he ends up being as freaked out by the experience as Jorgenson, and the two (O'Brien and Jorgenson, not Tim and Azar) become friends.
O'Brien arrives in Vietnam. He immediately impresses Kiowa by refusing to make fun of an old man's corpse, even though he did it more because he was scared than because of any moral principle.
Timmy falls in love with a fellow nine-year-old named Linda. She dies of a brain tumor, and he begins writing stories in his head to bring her back.