This book purports, not without justification, to be the definitive assessment of all the evidence for/against the existence of Nessie. By and large, it does an admirably thorough job, examining all of the available theories and trashing the most obviously ludicrous ones (I particularly like the way he treats the stupid hippy-idea that Nessie's image appears translucent on some photoes not because they are forgeries but because she comes from another dimension). He also mentions the tantalising existence of at least two films, apparently never viewed, that might conclusively establish the existence or otherwise of the beast, but which, due to a legal Snafu, are doomed to be locked away for ever in a London vault.
The only real fault of the book stems from the author's determination that Nessie not only does not exist, but cannot and indeed jolly well MUST not exist. This belief is pretty much evident from the tone and slant of the writing right from the beginning. Though the author purports to be completely objective, his take on the matter stands out precisely because he is NOT objective. How can he be? As Connor Cruise O'Brien pointed out in his essay on the French historian Michelet (in his collection of essays "Writers and Politics"), no-one writing a book about any given subject can really be objective, because anyone propelled to write a book on a subject must have some passion about it, and therefore some bias, in the first place. I could write completely objective books about, for instance, the history of Australian farming or Norwich City football club, but never would because I haven't got the remotest interest in either subject. This inbuilt bias leads the author to miss one or two aspects of the matter.
For instance, he states that Loch Ness has no egress to the sea. This is incorrect; the river Ness runs from the Loch to the sea - how does he think the migratory salmon get in and out? It follows that, if salmon can get to and from the sea, so could other organisms. Ones that live on them, for instance - though I concede that the likelihood of Nessie not being spotted in hot pursuit of salmon up a pretty small river is remote. Also, he claims that, if Nessie exists, she must have been spotted and even caught before now. This is a similarly fallacious belief; the recently-identified Megamouth shark has been around for goodness knows how long but was only discovered a few years ago, while the Coelacanth, thought to have been extinct for aeons, was discovered in the 1930s alive and well in the Indian Ocean, where it still thrives. There is an old Chinese saying - "What is the wisest animal? The animal that no man has seen". Nessie may yet exist, and prove to be smarter than anyone yet suspects. If those films ever get out, maybe we'll know for sure.