This 3-scene summary covers the key events and progression in the short story "Brown Sugar":
1) The story introduces friends Rachel, Mel, and Aster who go to a party at Stan's house, where Aster meets Billy. They bond over smoking outside.
2) One year later, Aster and Billy have begun a relationship and do drugs regularly with their friends. They increasingly isolate themselves, using more often just the two of them.
3) The story culminates with Billy introducing heroin to Aster. After they inject, she passes out and does not wake up, leaving Billy distraught by her death from an overdose.