Thompson describes in great detail the lives of the Hell's Angels and other so called outlaw motorcycle gangs. He gets into the heads of Sonny Barger, the leader of the Hell's Angels, and several other outlaws. He lets us see things from the Angels point of view; the one point of view never expressed in the mainstream press. Thompson realizes the necessity of uncovering both sides of a story in order for the truth to be revealed. The only way to write truthfully about the Angels is to join them and find out what makes them tick.
The book starts with Thompson weary of his relationship with the Angels, but that soon changes- although he never trusts the Angels. He notes that his friends become used to Hell's Angels hanging around his apartment any time of the day. Thompson drinks and does drugs with the Angels almost daily. He becomes so involved with the Angels that he buys a bike and joins them on several runs. He even helps to avoid a confrontation between the Angels and local town's people by volunteering to go on several beer runs.
Thompson mentions about half way through the book that he feels as if the Angels are sucking him into their lifestyle. He describes the Angels as men who feel lost in the mainstream modern society of high technology and business suits. Thompson comes to enjoy and respect the freedom of the Angels private society that shuns all laws restricting personal freedom.
He literally becomes swept away by their lifestyle like dust from the momentum of their bikes thundering down the highway.
Thompson eventually gets the hell beat out of him by a couple of Angels. One of the Angels, Tiny, rescues Thompson before he suffers serious injury, but he decides it best to sever his relationship with the group. The beating is unfortunate, but Thompson could not cover the story of the Hell's Angels without becoming personally involved. He never lies to the Angels about being a reporter, and they seem to respect him for his honesty; although the Angels hate reporters for all the bad press they receive. He tries to avoid conflict by blending in with the group and living their lifestyle. He becomes like a fly on the wall observing everything, but not interfering. The style allows Thompson to do something unheard of previously, report truthfully about the Hell's Angels. Thompson's final opinion of the Angels: "I wanted something original, but there was no escaping the echo of Mistah Kurtz's final words from the heart of darkness: 'The horror! The horror! . . . Exterminate all the brutes!'"