They Both Die at the End is a young adult romance novel written by American author Adam Silvera and published on September 5, 2017, by HarperTeen. It is Silvera's third novel and focuses on two teenage boys, Mateo and Rufus, who discover that they only have one day left to live. In April 2020, due to #BookTok, the book's popularity saw a resurgence, once again placing it on The New York Times Best Seller list.