This book is "Rich" Haier, Professor Emeritus in the Pediatric Neurology Division of the School of Medicine at the University of California, Irvine, writing to his students. He wants to tell them about the three-pronged nature of contemporary research into intelligence: psychometric tests (delivering 'g'), neuro-imaging and genomics.
Leveraging all three approaches, he comprehensively demolishes blank-slate ideas that intelligence doesn't really differ between individuals, genders and/or ethnic groups, and shows that intelligence differences (as measured psychometrically or in life outcomes) have measurable correlates neuro-anatomically and genetically.
Since higher IQ correlates positively with desirable life outcomes, he is a strong proponent of research which might lead to future IQ improvements, either through some kind of 'IQ pill' or targeted allele-engineering.
Haier is plainly an experimentalist, not a theoretician. He is happiest explaining the details of studies, neuro-imaging equipment and brain images: he's almost too thorough. He is also good on the unexpected results: when men and women with identical (and high) mathematical abilities were scanned while solving advanced math problems they were equally successful - but the men used the spatial parts of their brain while the women were using verbal modules.
While we are plainly in the middle of a technology-led revolution (well-described at an introductory level) it's frustrating that the jury is still out on all the important questions. We don't know what the brain is doing which distinguishes consciousness from unconsciousness; we don't really know how the high-IQ brain differs in structure or function from the low-IQ brain although there are some suggestive ideas; we don't know how to alter/improve IQ by any well-attested intervention.
Perhaps this will change over the next few years. Given the stigma which still attaches to intelligence research in the West, perhaps we'll have to wait for the Chinese to tell us.