Darkness and Dawn

This is a novel book. They then wander through the rest of the story having incredible adventures to rival the pulps of the classic age, express their love for each other (for pages and pages and pages), have more incredible adventures they survive by the skin of their teeth, express their love for each other for many more pages, express their disdain for religion and capitalism, face death square in the chops, express more of their love for each other, express how the new world they are going to rebuild will be a socialist paradise, fight to the death with a monster or two, express their love for each other, and. . . well, you get the picture. Along the way we learn that concrete and steel are eternal, that 1, 000-year-old food in the tin still tastes good, that Allan can rebuild a pre-WWI plane from deer hides, that fur coats stored carefully for a millennium can still be worn, that people can go into suspended animation and wake up with the clothes rotting off their bodies without any harm to themselves (or even feeling hungry), that a ten-century-old bullet can still fire without any problem, that air pressure does not change to any serious degree if you go to the bottom of a canyon that is well over 50 miles deep, and did I mention that concrete will outlast the heat death of the universe?