Tribute by Kristine Kathryn Rusch

Lt. Kenyon fulfills his duty to serve his country and the war effort by censoring the crew’s letters home, even though it means that his shipmates hate him. But when the crew begin writing about a ghostly vision—a vision impossible to believe but inadvisable to ignore—he must address the danger facing the ship and her crew. And he must make a choice that will affect every last man on board.