by Terry Pratchett and Neil Gaiman

A J Crowley and Aziraphale have been on earth for millennia - well, since the beginning really. Crowley is one of the Fallen (who did not so much fall as saunter vaguely downwards) and was originally the serpent who suggested to Eve that those apples looked particularly tasty. Aziraphale managed not to fall but is in a certain amount of trouble for taking on pity on Adam and Eve and helping them out a bit by giving Adam his flaming sword

The two have become friends of a sort and rub along quite nicely doing their thing, maintaining the balance, until Crowley is charged with the placement with a suitable family of the son of Satan. The idea is that once the child reaches adolescence he will bring about the end of the world allowing Crowley and Aziraphale to go their separate ways, one up and one down, and giving this poor planet a break. Neither one of them is sure that they want this to happen because Hell is sort of hot and Heaven is kind of boring and they really like it here on earth

With a cast of witches and witchfinders, a jezebel/medium, several children, a book of prophecies that are actually accurate, not to mention the four horsemen of the apocalypse - due to advances in modern medicine pestilence has been replaced by pollution but it seems to work okay - this is Pratchett at his best and a reminder to me to look out for some Neil Gaiman whose work I've yet to read