The Junky's Christmas (plot summary from Wikipedia)
Penniless and withdrawing from opiates, Danny emerges from a 72-hour stay in a police holding cell. Hoping to make enough money to buy his next hit of heroin, he scours the streets looking for something to steal. After an unsuccessful attempt to break into a parked car, he discovers an unattended suitcase sitting in a doorway. He makes off with the case and takes it to an abandoned park to examine its contents. There he finds that the case contains two severed human legs. Disgusted, he discards the legs and tries to find a buyer for the suitcase. He finds a buyer who gives him three dollars but also informs him that the local heroin dealer has been arrested.
Unable to find heroin anywhere Danny decides to visit a doctor with the hopes of obtaining some morphine. When he reaches the doctor’s house he pretends to be suffering from facial neuralgia. The doctor is suspicious but gives Danny a quarter of a grain of morphine free of charge.
Drugs in pocket, Danny rents a room for two dollars. As he prepares to inject the morphine, he hears groaning coming from the next room. Distracted, he follows the sound of the groaning across the hall to find a young man suffering from kidney stones. Danny offers to call an ambulance, but soon realizes that the paramedics will not come as they believe the young man is faking illness to obtain opiates. Danny selflessly administers his morphine to the young man. The morphine immediately alleviates the young man’s pain. Danny returns to his room. All of a sudden he begins feeling the effects of heroin; it appears that his good deed has been rewarded with “the immaculate fix.” Danny nods off to sleep.