The apocalypse is over, adam went back to being normal, heaven and hell left aziraphale and crowley alone and they got married. But this story isnt about them. Its about a technical 25 (7000) year old with gender identity problems and is pretty much dating the archangel gabriel when god tells them "im giving you custody over the antichrist because hes your half brother, ok byeee" so now its their job to take care of the literal antichrist (there will be a sexual reference in every chapter, some strong, some vauge)

In a rushed, hurried panic, Gabriel goes to Aziraphale's bookshop, needing a tad but of help... Just Gabriel being dumb