Aziraphale, an angel (originally a guardian of the Eastern Gate of Eden), and Crowley, a demon (originally the serpent who tempted Eve), have lived on Earth since its creation. Over the millennia, they have formed an odd relationship and taken a liking to humanity. One night, the forces of Hell deliver the infant Antichrist to Crowley, with instructions to swap him with the son of an American diplomat stationed in Britain. Crowley realizes this means that the Apocalypse is coming and persuades Aziraphale to help him prevent it.
