“Truth isn’t guaranteed,” says the Oscar-winning documentary director Errol Morris, whose first book, Believing Is Seeing: Observations on the Mysteries of Photography, comes out September 1. “It’s something you pursue that involves investigation.” Morris briefly worked for a famous private investigator, and each chapter here, he says, “is a mystery story about a photograph,” among them a shot of Abu Ghraib and one of the 2006 Israeli-Lebanese war. The book is also very personal—get a load of Morris’s own wedding portrait, taken by Tom Waits.