This is really a 3.5. In general, an excellent book focusing on one of the most intriguing characters from the pirate hall of fame. William Kidd in many ways epitomizes life at the turn of the seventeenth/eighteenth century - there is patronage and betrayal, intrigue, politics, the Whig/Tory scuffles, the East India Company, the beginnings of globalization and the financial revolution: all jolly good stuff. In the main, Ritchie explores this world on the cusp of modernity exceedingly well, with a strong narrative voice, an ability to explain with condescension, and good use of the reams of extant sources.
The relatively low score might be a little petty. However, the introductory chapter contains a reasonable amount of dross, a few of the references have led me on a wild goose chase, there are a few too many bees coming loose from his bonnet, and he made the unforgivable error of calling Pepys 'William'.