I first read this book over twelve years ago and my admiration for it has never waned. Unlike many Shroud of Turin theorists whose conclusions rely largely on speculation and/or anecdotal evidence, Dr. Heller is one of the very few people who have scientifically tested actual samples taken from the cloth. He conducted his experiments over a period of several years in an attempt to determine the chemical nature of the "blood" and "image", and how they got on the Shroud in the first place. How the image formed he never determined, but through chemical testing he found it to be the result of acid oxidation of the linen. The "blood" he concluded to be actual blood by over ten different tests including spectral analysis, and chemical identification of bile pigments and serum albumin. The book, however, is not all dry Science. It tells the funny and interesting story of Heller's involvement in the Shroud of Turin Research Project from beginning to end. He doesn't hold the you, the reader, at arm's length--he takes you right into lab itself revealing in detail not just the experiments that he and his collegues performed, but also something of their personalities and motivations. Many scientists and skeptics today either ignore or write off Heller's work in a few curt sentences, but Heller's use of control experiments to test and retest his conclusions give his work credibility. Whether the Shroud is real or fake makes no difference to me, but ANY source skeptical of the Shroud's authenticity who cannot or will not give a convincing, detailed, point-by-point refutation of Heller's conclusions I would consider suspect. Only when such a source comes forward (and I have not yet seen one to date) will the matter be settled in my mind.