Author and physicist Paul Davies takes on a subject likely to be met with hostility by many readers, and most especially by physicists and religious believers. His question is: why does the universe exist, and why is it hospitable to life, especially sentient life? These are questions on the boundary of science, and it may be that there is not, even in principle, scientific answers to these questions. A scientific theory must have 2 characteristics: explanatory power, and falsifiability. It seems likely that there is no observation or experiment that could be performed that could test any theory of why the universe exists. Almost by definition, the answer to that question would involve something that 'came before' or 'lies outside' the observable universe. I put quotes around those phrases because many physicists would argue that time and space themselves emerged as part of the big bang, so any reference to 'before' or 'outside' would be meaningless.
And of course many religious believers are likely to take offense at the very idea that science might provide answers to these questions. The history of science and of religious belief over the past few centuries has been one of science steadily chipping away, and sometimes gouging large holes out of, the realm of religious speculation and belief. In the United States there are an amazing number of people who are unable to accept the basic facts of biology, specifically evolution by variation and natural selection. There's just no arguing with those people - they have abandoned reason. But more 'reasonable' believers continue to take comfort in the idea that questions of the ultimate origins of the universe are outside the realm of science and are therefore, by a strange sort of logic that I do not understand, in the realm of theology. Unfortunately for this idea, the same objections and absurdities that plague any attempt at a scientific explanation of the 'why' of the universe apply with at least equal force to the theological explanations.
Davies proposes many theories, some of which involve a kind of causal loop between mind and cosmos. Others are somewhat more orthodox (if that word even has meaning here), such as quantum multiverse, infinite quantum multiverse, platonic necessity, and so on. At the end, though, Davies admits that on reviewing those theories they all strike him as ridiculous.
If all of the theories are ridiculous, we are back where we started, except that the mysteries seem, if anything, deeper and more perplexing than before.
Davies makes some interesting points about mathematical Platonism, and its cousin, the idea that physical laws have a kind of platonic reality. Most mathematicians are Platonists, in the sense that they believe that mathematical truth is 'out there' waiting to be discovered; that theorems are are discovered, not invented. The alternative to this view would be that theorems are invented. This alternative would seem to imply that the theorems of mathematics could in principle be invented differently; but it is impossible to conceive how this could be so. There is an inherent non-contingency in mathematics. Even the Godel incompleteness theorem does not disturb this: Godel only proved that axiomatic systems cannot be both complete and consistent; i.e. there are true mathematical theorems that cannot be proved within any particular consistent axiomatic system. Note that the 'truth' of the theorem (i.e. its existence in some platonic realm) is something that exists outside of the possibility of proof (where the proof is indeed something invented by human ingenuity).
Davies claims, plausibly, that most physicists are also Platonists with regard to physical laws, at least at some level. Even physicists who believe that the current values of physical constants 'precipitated out' of the big bang, believe that there are underlying laws, perhaps as yet undiscovered, that exist somehow outside of the physical universe, and that guide the evolution of the universe, and more significantly, that drove the creation of the universe. When you put it like that it all seems mind bogglingly mysterious, and fundamentally implausible.
You won't learn much physics from this book, and you won't come away with any answers to the questions Davies raises. But you will have a better understanding of just how implausible it is that we and the universe exist at all.