Hal Jordan, the Green Lantern of Earth, meets and trains his new designated substitute - John Stewart, DC Comics's first black superhero.
We open with an earthquake in southern California, and GL flies to the rescue. He sees Guy Gardner trying to help people, but Gardner's struck and critically injured by a bus, requiring months of hospitalization and recovery. A Guardian of the Universe, who oversee the Green Lantern Corps, have selected John Stewart, an architect, as his new alternate. However, Jordan is appalled by Stewart's lack of respect for authority (even when that authority is bigoted and racist), but the Guardian insists. Jordan commences training Stewart in the ways of the Green Lanterns, but their first mission together goes awry.
This story was part of Green Lantern's famed "Hard Traveling Heroes" days, when Green Lantern and Green Arrow confronted various social ills and white-collar criminals. (By the way, if you're wondering where Green Arrow is in this comic, he has a backup story in this comic where the death of a kid during a civil rights protest inspires him to run for mayor of his home town of Star City.) While the stories from this era could be heavy-handed in their execution - this one included - they're still well-told, and helped a lot to demonstrate that mature storytelling could indeed be found in comic books. Stewart's introduction, contrived as it may be (although no more so than most other superhero origins), is an effective one. I'm not in a position to judge Stewart's in-comic characterization and personality, except to note how it would change over the decades as he became more somber and introspective, especially after his infamous failure to save the planet Xanshi from destruction. I will say that he's certainly a relatable character, and Jordan's judgmental attitude toward him comes off as overly harsh (as I'm sure it was designed to).