Mark of the Devil — William Kerr

Navy Special Warfare officer Matt Berkeley is on a new hunt. Under the seas off the coast of Florida, in a corpse-filled German U-boat, he finds a document lost for more than half a century, which leads him to the vaults of the German National Archives, an elderly widow and her horrifying memories of the Auschwitz death camp, and ultimately to the submarine's most guarded secret--a revelation that could forever disgrace the Catholic Church in the eyes of the world. Each mind-shattering twist plunges Berkeley further into a conspiracy littered with lies, betrayal, death, and the discovery of a single gold ingot bearing the mark of the devil.