Crowley and Aziraphale are now living together in Crowley's apartment. The story follows them and their every day lives a year after they helped Adam Young stop the apocalypse. Gabriel pays Aziraphale a visit to announce that he is exiled from Heaven for the next 2000 years, and no angel will come to Earth during that time since they will regroup in Heaven (as demons will regroup in Hell) getting ready for the next big battle. Aziraphale and Crowley are thus left (alone) on Earth. If you loved episode 3, where it was just them throughout the ages - then you will love this story.