The instant New York Times bestseller from the author of the international sensation The Rule of Four combines a lost gospel, a contentious relic, and a dying pope’s final wish into a “deliciously labyrinthine” ( Providence Journal ) intellectual thriller that “kicks off at ninety mph and doesn’t slow down” (Associated Press). A mysterious exhibit is under construction at the Vatican Museums. The curator is murdered at a clandestine meeting on the outskirts of Rome a week before it opens. That same night, a violent break-in rocks the home of Greek Catholic priest Father Alex Andreou. When the papal police fail to identify a suspect in either crime, Father Alex decides that to find the killer he must reconstruct the secret of what a little-known, true-to-life fifth gospel known as the Diatessaron reveals about the church’s most controversial holy relic. But just as he begins to understand the truth about his friend’s death and its consequences for the future of the Christian church, Father Alex discovers a ruthless stalker is hunting him—an enemy with a vested stake in the exhibit that he must outwit to survive. Rich, authentic, erudite, and emotionally searing, The Fifth Gospel is a riveting novel of suspense and a feast of biblical history that satisfies on every level. “Spectacular . . . Caldwell knows his Vatican, and in his detailed descriptions of hidden gardens, underground car parks, piazzas, dark lanes, tunnels and corridors, conjures up a strange and alien realm where hierarchy is all, secrets fester and multiply, deals are spun behind closed doors, and a murderer may be on the loose. . . . This superb Rubik’s Cube of a novel is the best of its kind, right up until the final shock and the pope’s dying wish. . . . Deliciously labyrinthine.” — Providence Journal “A stunning and addictive read . . . Part murder mystery, part family drama, part religious history, this keep-you-on-edge literary thriller doesn’t miss a beat. Caldwell’s elegant language combines with a truly provocative plot . . . Obsessively readable.” — Library Journal , Editors’ Spring Picks “A novel of betrayals and cover-ups, but mostly of sacrifice, of commitment and of love, with credible characters, twists and turns of plot, and a fascinating theological rationale . . . Although the mystery and the tension mount inexorably throughout the novel, there’s none of the cheap end-of-chapter cliffhangers beloved of hack thriller writers. Everything in The Fifth Gospel rings true because Ian Caldwell spent ten years researching and writing the novel.” — The Catholic Herald “The second novel from Ian Caldwell, coauthor of the bestselling The Rule of Four , kicks off at 90 mph and doesn’t slow down. Caldwell’s skill as a writer is evident in his ability to weave detailed descriptions of Biblical scripture, Catholic history, and Vatican geography into the story while keeping the action going. . . . He has created memorable characters with complex relationships, deep love, and longstanding hurts. . . . Ultimately, Caldwell’s novel is about faith—in God and in family.” —Associated Press “This beguiling, brainy thriller . . . integrates pulp plotting and scholarly speculation . . . A mixture of courtroom drama, whodunit, and alternative history.” — Sunday Times (London) “It’s been ten years since Ian Caldwell co-wrote The Rule of Four . The Fifth Gospel was more than worth the wait. For those who might compare it to The Da Vinci Code , don’t. This marvelous book stands alone and will become the very high standard for any novel in this genre. Masterfully plotted and extraordinarily researched, and written in a voice that never rings false, The Fifth Gospel is that rare story: erudite and a page-turner, literary but compulsively readable. It will change the way you look at organized religion, humanity, and perhaps yourself.” —David Baldacci “You are going to hear a lot about how this book took ten years to write and how it’s minutely researched and erudite. Forget all that. This thing reads like a rocket. Jump on and hold tight.” —Mary Doria Russell, author of The Sparrow “An amazing achievement: The Fifth Gospel is a gripping thriller rich with human drama and forbidden knowledge.” — Lev Grossman, author of the Magicians trilogy “ The Fifth Gospel is nothing short of groundbreaking—a literary feast wrapped around an intriguing murder mystery. Caldwell writes with precision and passion as he takes us on an emotional journey deep into the workings of the Vatican and deeper into the hearts and souls of the men and women who have devoted their lives to the Church. The Fifth Gospel is a cathedral where skeptics and believers alike may enter and all will leave transformed.” —Nelson DeMille “Under Caldwell’s deft hand, the Vatican becomes a setting both real and surreal, utopian and dystopian by turns, a tiny, walled country where the switchboard operators and nannies are nuns, the cops are Swiss