S.E. Hinton: That Was Then, This Is Now is about Bryon, the novel's sixteen-year-old narrator, and his friend Mark grow up in an American inner city district during the early seventies. Since Mark's parents have shot each other in a drunken argument when he was nine years old, Bryon's mother decided to take him home in order to take care of him. Bryon and Mark have been as close as brothers from this moment on, both living in a harsh world of gang fights, alcohol and drugs: "It was great, we were like a bunch of people making up one big person, like we totaled up to something when we were together.” It turns out that Bryon and Mark are not only used to brutal street fights, but also to stealing. Bryon knows that stealing is wrong, Mark, however, sees it more like a game. Stealing is something to do for fun and profit to him and - since nobody has ever caught him - it can be a useful talent in rough times.
One of the most brutal acts of violence described in the novel takes place in front of Charlie's bar. The bartender, Charlie, who is one of the very few good friends of Bryon, gets involved in a gunfight with two Texan pool players and dies when he tries to defend Bryon and Mark. Realizing that he has lost an irreplaceable friend, Bryon starts to think about life more seriously, while Mark keeps living for the thrill of the moment. On top of that, Bryon begins to spend more time with his girlfriend Cathy, which was the first girl he really loves. Mark and Bryon are growing apart: Mark even acted like he was jealous of Cathy. In all the years I'd known him, in all the years I'd gone with different girls, he had never like that. I was changing and he wasn't. Cathy's brother, who is called M&M even by his parents, seems to be as intelligent and brilliant as his sister. He is, however, dependent on Mark and Bryon's protection because of his non-violent nature.