No, there is a second nuclear war. Some people escape on rockets, but human life on earth is ruined.
The author was an American bomber pilot in the second world war, and took part in the bombing of ancient church buildings in Italy. After the war, out of guilt, he became a Catholic wrote the book. He seemed to share the same kind of pessimism that George Orwell had, having lived through one destructive war only to see another war come on the horizon.
It's a very good book, and despite its themes it is readable and in parts humourous (especially the first section).