American Eleanor Shellstrop has just passed away, her spirit's final resting place being "the good place" (as opposed to "the bad place" where most go after they die). Spirits in the good place live in specially designed neighborhoods - Michael being the architect of Eleanor's neighborhood - with a small group of the best of other good spirits.
All spirits are paired with soul mates, Eleanor's being a Senagalese ethicist named Chidi Anagonye. The entire situation is meant to be paradise for the residents, but this Eleanor Shellstrop is not the Eleanor Shellstrop Michael believes her to be, this Eleanor was selfish and self-absorbed, an attitude she takes into the good place.
Based partly on what little she knows about the bad place, Eleanor wants to stay in the good place, which means that she is constantly looking over her shoulder so as not to be caught as a fraud, specifically by Michael. She also wants to turn her attitude around so that she deserves to be there, which she hopes to do with the help of her soul mate.
But if Eleanor does not belong in the neighborhood, what else could be wrong with the good place?".