On the Beach, by Nevil ShuteRead about another entry on the list.
Nuclear war is, sadly, still one of the most likely ways civilization and all human life could end on the planet. Set largely in Australia as the population awaits a huge cloud of deadly radiation stemming from a nuclear war in the Northern Hemisphere, the story remains a gripping and horrifying glimpse of an end of the world that could still happen—at any time.
Plausibility rating: One tweet more likely, anyway.
On the Beach is among Rebecca Jane Stokes's seven books not to bring to the beach, Ben H. Winters's three books to read before the end of the world, Sloane Crosley's five depressing beach reads, and Michael Evans's top six books on nuclear war.