When he was a kid, Crowley had an imaginary friend named Aziraphale. He was a prince who lived in a castle on the other side of a magical bookshelf. Normal kid stuff, right?
Now that Crowley is a well-adjusted middle-aged professional, the last thing he expects is for Aziraphale to come crashing back into his life. But the prince is very real, and very determined to avoid the war that his brother, King Gabriel, is equally determined to drag him into. Crowley finds himself simultaneously introducing Aziraphale to modern technology, trying to protect him with the help of his belligerent lawyer cousin Bee, and falling in love faster than he can keep up with his own feelings.
Oh, and there's also a couple of witches. Things are about to get complicated . . .