The book is called “Nuclear War”, the author is Annie Jacobson. Using around 50 experts and tons of references from the military, CIA, nuclear scientists & professors, she goes through a minute by minute and often second by second account of what would happen if N. Korea fired just one ICBM with a thermonuclear warhead at the Pentagon. Minutes later they fire a second missile from a submarine just outside of California aimed at a nuclear power plant in CA. Pretty astonishing.