This is an excellent book, published just a few months ago. It deals with the year of the title, early in the reign of James I; the year that Shakespeare wrote three of his greatest plays: "King Lear", "Macbeth" and "Antony and Cleopatra". The purpose of the book is to explain important recent events which would have been passing through Shakespeare's mind as he wrote. The most famous of these was, of course, the Gunpowder Plot of the previous November, and the trial and execution of the plotters in January. Since they were almost all Catholic landowning gentry from the Midlands, they would have had links with Shakespeare's Stratford-on-Avon, and at least one of them, John Grant, could well have been known personally by Shakespeare. Early in 1606 there was a quite separate rumor that King James had been assassinated, which caused a panic in London. There was also a famous case of demonic possession which was then exposed as a hoax, the King's unsuccessful attempt to bring about a full union between England and Scotland, a royal state visit (a very rare event at the time) from James's drunken brother-in-law Christian IV of Denmark, and a severe outbreak of plague which closed the London theatres from much of the year. So: a very eventful time, which must have influenced Shakespeare's thinking in one of his most creative periods.
This book is strongly recommended!