Very dense and detailed, with 500 packed pages of historiographically-informed narrative, which is one reason it took me six and a half months to finish.
Harris' focus is upon the reign of James VI & I from the time of his accession to the English throne, and the reign of Charles I from his ascending the throne in 1625 until the outbreak of the English Civil War in 1642. Primarily an English focus, but with extensive sections devoted to Scotland and Ireland. In spite of the somewhat misleading title, Harris does not believe that the outbreak of violence in the "Wars of the Three Kingdoms" in the 1640s was inevitable, but was rather the result of short term policy decisions and the practical ineptitude of Charles I.
The book is based upon a close reading of recent work by scholars on both sides of the Atlantic, and includes an immensely helpful and lengthy section of endnotes (63 pages of rather small print, and that does not include the list of primary sources consulted, nor the "Guide for Further Reading." Thank you OUP for including these in the printed book, where there belong, and not merely directing interested readers to some obscure location on the interwebs.)