U.S.-China competition is one of the defining stories of this era, but it has stopped short of violence, for now. In the novel "2034," Admiral James Stavridis, former NATO supreme allied commander, and Elliot Ackerman, a best-selling author and former Marine, imagine a naval clash between the two nations in the South China Sea in the next decade--and the path from there to a nightmarish global conflagration. How can we avoid this dark future?