The Final Descent is a horror novel by Rick Yancey, the fourth and final book in a series that he inaugurated in 2009 with The Monstrumologist (UK title, The Terror Beneath). It was published in September 2013 by Simon & Schuster Books for Young Readers, which recommends it for reader ages 14 and up, grades nine and up.The U.S. Library of Congress catalogs The Final Descent as written by William James Henry and edited by Rick Yancey. Will Henry is the boy lead character of the series and William James Henry is a pseudonym of Rick Yancey. Source: Wikipedia (en)