Bryon and Mark are best friends. They have lived together with Bryon’s mother ever since Mark’s parents shot each other in a drunken brawl. The boys hang out at Charlie’s Bar and earn money by hustling pool. Charlie tells the pair that M&M, a younger Hippie boy, is looking for them. Bryon and Mark find M&M in time to stop Curly Shepard and his Greaser gang from beating M&M up. The “Hippies” are a new group and the lines between the two former groups, the “Greasers” and “Socs,” are becoming blurred.
The following day, Bryon and Mark visit Bryon’s mother in the hospital. While there, Bryon meets Cathy Carlson, M&M’s older sister, who works in the snack bar. Bryon is taken with Cathy and hopes to see her again. Bryon and Mark also visit Mike Chambers, a boy Bryon’s mother befriends. Mike is recovering from a beating after being falsely accused of harming a young African American girl. Mike tells Bryon and Mark what happened, how he actually saved the girl from being harassed by a group of whites. Mike drove the girl home and his car was surrounded by a group of African American kids. They pulled him from the car and nearly beat him to death when the girl lied, claiming Mike hurt her. Despite the beating, Mike does not hate African Americans. When he thinks about it from the girl’s viewpoint, he can almost understand why she lied. After the visit ends, Bryon and Mark discuss Mike’s misfortune. Mark does not share Mike’s understanding of the factors that caused the girl to lie. Mark states that if anyone ever hurt him like that, he would hate them forever.
Mrs. Douglas’s hospital stay causes financial stress. The boys are forced to look for jobs, but they do not have much luck. Bryon asks Charlie for a job. Charlie refuses because Bryon is underage. Charlie also doubts Bryon’s honesty in certain areas, though he does trust Bryon enough to loan him his car so Bryon can take Cathy to a school dance.
At the dance, Bryon’s former girlfriend, Angela Shepard, starts a fight intending to punish Ponyboy Curtis for failing to respond to her advances. Unfortunately, Mark is the unintended recipient of a bottle to the head. Bryon leaves Cathy at the dance and goes with Mark to the hospital. Mark gets stitched up. Ponyboy hotwires Charlie’s car and brings Cathy to the hospital. Bryon takes over driving duty, dropping off Ponyboy and Cathy and finally taking Mark home. The boys stay up talking. Mark tells Bryon that even though they are not blood relations, he feels like they are “real” brothers.
After Mark recovers, the boys go to Charlie’s Bar to make some money hustling pool. Bryon manages to hustle a couple of Texans, who are not happy to lose their money. The Texans wait for the boys outside, intent on teaching them a lesson. Charlie realizes the boys are in trouble and attempts to save them. The boys witness Charlie’s death when the Texans shoot him.
In the weeks that follow, the boys struggle to make sense of Charlie’s death. Meanwhile, the financial strife at home grows worse. Mrs. Douglas is hospitalized again. Mark gives Mrs. Douglas money but will not reveal where it is coming from. Mark grows distant. Bryon finds himself frequently turning to Cathy for support instead.
M&M disappears. Bryon and Cathy search but do not find him. Bryon and Mark get Angela drunk and cut her hair as payback for Mark’s injury in the earlier fight. Mark is jealous of Cathy, and the distance between the boys grows. Bryon questions whether he knows who Mark really is. The Shepard brothers beat Bryon up for cutting Angela’s hair, but, instead of retaliating, Bryon chooses to deal with them by not hating them, a lesson learned from Mike’s experience with the African Americans who beat him.
Mark lets it slip that he might know where M&M is. By the time M&M is found, he is on a bad acid trip. He is hallucinating and scared. Bryon and Cathy take him to the hospital. The doctors try to treat him, but there is no guarantee that he will make a full recovery. Later that night, Bryon discovers a container of pills in Mark’s room. He realizes that Mark has been making money selling drugs and may even be the one responsible for M&M’s condition. Bryon calls the police and turns Mark in.
Mark is sentenced to five years in the state reformatory. Bryon distances himself from everyone, including Cathy. Later, Bryon visits Mark in prison. Mark tells Bryon that he hates him. Bryon tries to apologize but Mark will not listen. Bryon pleads for forgiveness, reminding Mark of their friendship and brotherly bond. Mark turns Bryon’s words against him when he says, “Like a friend once told me, ’That was then, and this is now.’” Bryon leaves, numb and worn out, wishing to be a kid again, at an age when he seemed to have all the answers.