Here's the condensed version of Jazz: A married dude shoots his eighteen-year-old girlfriend, and she dies. His wife is understandably bummed out. Everyone sits around thinking about history and listening to jazz for a few months. Another eighteen-year-old girl shows up, and the married couple dances and is happy again. Fin.
But that's seriously like giving you a thirty-second sample of Miles Davis's Sketches of Spain and saying "Yeah? Do you like it? Do you get it?" So let's try to give you something a little meatier.
Okay, Joe and Violet Trace's marriage has fallen into ruins because Joe had an affair with an eighteen-year-old girl and then shot and killed her. Not exactly a recipe for domestic bliss. Violet does what any sane woman would do and tries to cut the face of the dead girl—named Dorcas—at the open-casket funeral. Okay, we rescind our sanity judgment.
Now their house is, to put it mildly, a tad troubled. The silver lining in this tears-and-misery cloud is that they live in New York City. An unnamed narrator that floats about the book, peering into the recesses of everyone's consciousness, talking a lot about how shiny and splendid and sexy New York is.
Joe really acted like a scumbag, but we get a little bit of information about Violet's odd behavior prior to Dorcas's murder. She was trying to steal babies, talking nonsense, and carrying a baby doll. So yeah, the whole having-an-affair thing makes a little more sense now.
Violet and Joe met under a tree in Virginia during cotton-picking season. They fell in love, lived together for a long time, and eventually made their way up to New York City in 1906. But despite the fact that Joe and Violet had what sounds like a rocking good marriage, she went a little nuts and he got a case of the old wandering eye. Enter Dorcas. She and Joe carry on their affair in an upstairs neighbor's apartment. The neighbor works nights, so Joe and Dorcas have ample time to fool around.
We learn about Dorcas's Aunt Alice, who is a super-strict and super-pious woman who essentially thinks that jazz music is the devil using a megaphone to lure otherwise good kids into a life of sin. Fast-forward to just after Dorcas's death, when Violet and Alice become friends. Instability seems to run in Violet's family: Her mother committed suicide and she was raised by her grandmother, True Belle. For his part, Joe never knew his parents, but was raised by a kind family.
We now leave New York and the Joe/Violet drama and do some serious time travel.
Say hello to 1854, where the white daughter of a wealthy slave owner is knocked up, and the father of the illegitimate baby is a black man. The baby turns out to look almost totally Caucasian, so he's raised in relative peace until his eighteenth birthday when he finds out, courtesy of True Belle, that his father is black.
He decides to go find his father, but on the way through Virginia he encounters a naked, pregnant, and unconscious black woman. As he meets his father the unconscious girl wakes up and gives birth to a baby boy. The boy ends up being none other than Joe Trace. The mother, nicknamed "Wild," abandons Joe and runs off into the woods.
We time-travel back to wintery 1926, when Joe is stalking Dorcas. Joe shoots Dorcas as she is dancing at a jazz party where illicit stuff like gin-drinking and dancing cheek-to-cheek happening. Yowch.
Enter Felice, Dorcas's friend, and fast-forward to the spring of 1926. Felice goes to see Violet and Joe for a whole slew of complicated reasons. Weirdly enough, they all get along like a house on fire. Joe starts becoming happier, and Violet feels like she has a daughter, and they all dance. To jazz music.