Penguin Random House published "River of Bones", the thirteenth book in the series, in July 2018 to generally favorable reviews. The machinations of the League of Tripoli continue as do the wars against the Grik and the Doms. Matthew Reddy is forced to command a new ship, as the "Walker" is too badly damaged. More details are given about the group of people calling themselves the "New United States", the descendants of American soldiers who were originally being transported in 1847 on oceanic vessels across the Gulf of Mexico as part of the amphibious assault on Veracruz during the Mexican–American War.