Written in verse and narrated in the first person by Will Holloman, a fifteen-year-old Black American, Long Way Down opens with Will revealing that his older brother, Shawn, was killed two days earlier.
Will goes back to the day, explaining that he is talking with his friend Tony when Shawn is shot outside their building. Their mother is distraught and moaning, while Shawn’s girlfriend, Leticia, kneels over the body and screams. Will notes that the killers didn't steal Shawn's gold necklace. When the police come, none of the witnesses will say that they saw anything. This happens with every shooting because The Rules dictate that nobody ever snitches.
Will returns to his mother's eighth-floor apartment and listens to his mother sobbing in the kitchen. He lies in his bed and suppresses his tears, because The Rules for dealing with the death of a loved one are: 1) No crying, 2) Don't snitch, and 3) Get revenge by killing the killer.
Will finds a gun in Shawn’s dresser. He sleeps with it under his pillow and slips out of the apartment while his mother is asleep. He plans to shoot Carlson Riggs, a former friend of Shawn’s, who belongs to the Dark Suns gang. Will is convinced Riggs must have been the killer, despite the fact that he didn't see the shooting.
Will gets in the elevator to go down to the lobby. However, he is visited by the ghost of Buck, a local gangster who was once a father figure to him and Shawn. Buck teases Will, implying that he does not have it in him to exact revenge. Buck also reveals that the gun in Will's waistband used to belong to him. Will attempts to act like a gangster, although he has never fired a gun. Buck lights a cigarette and the elevator stops on the next floor, having moved incredibly slowly between floors.
An attractive girl Will's age gets on. Will flirts with her until she reveals she is Dani, a childhood friend who died before Will's eyes when they were eight. Dani asks will whether he has considered the possibility that he could miss his shot, potentially harming an innocent bystander. This is how Dani was killed.
On the next floor, the ghost of Will's uncle Mark steps on. Uncle Mark is friendly with Will, but also challenges him on his certainty that he is capable of killing Riggs. Will digresses to tell the story of how Mark was killed in a battle for drug-dealing turf after he started selling drugs to earn enough to buy a camera and be a filmmaker.
On the next floor, Will's father gets on the elevator. Will has no memories of his father, but he feels an immediate connection when they hug. The reader learns that Will's father Mikey died because he tried to abide by The Rules and avenge Uncle Mark’s death. However, Mikey ended up killing Gee, the wrong man. In retaliation, someone close to Gee shot Mikey. It was after this happened that Buck became a mentor to Shawn. Mikey ends up taking the gun from Will and holding it to his head, making son wet himself in terror. He then returns the gun to Will and lights a cigarette Buck gives him.
The next ghost is a man named Frick. Will learns that Frick killed Buck during a Dark Suns gang initiation that went wrong. Frick had only wanted to rob Buck, but he shot him when Buck fought back. Frick then died when Shawn shot him. Will learns that the single bullet missing from Shawn's gun is the bullet that killed Frick. Will gets excited by the idea that Riggs, also associated with the Dark Suns, must have killed Shawn in retaliation, but Frick has never heard of Riggs.
The final visitor is Shawn, who is in the clothes he was in when he was murdered. Shawn greets everyone else in the elevator but won't speak to Will. Will wants confirmation that he is doing the right thing in following The Rules and targeting Riggs, but Shawn won't answer his questions. As the elevator fills with cigarette smoke, Will becomes increasingly distressed. He wants to leave the claustrophobic space of the elevator, which has become like a vertical coffin. The novel ends with the doors opening at the lobby and the ghosts walking off. Shawn turns around and asks Will if he's coming.
