By providing several chapters of background on Virginia politics, Jefferson's early life, career, and relationships, and the early years of the Revolution in the state, Kranish lays the groundwork for the main event, an in-depth reconstruction of the British assault on Virginia (led for a time by the traitor Benedict Arnold) and Jefferson's actions to combat the invasion and then, when the time came, to flee from it.
Putting Jefferson's escape into the context of the political, social and military situation in the state as the British drew nearer, it's really a surprise the whole thing didn't go even worse. Given the state of intelligence-gathering, executive authority, military readiness, &c., it actually is quite amazing that the entire governmental and military apparatus of the state wasn't completely demolished.
Kranish does well here in recreating the scenes, and provides some really fascinating anecdotes to weave into the fabric of the story, including the saga of John Champe, a Continental soldier who infiltrated British lines in New York under Washington's orders in a scheme to kidnap Benedict Arnold, but misses the chance and ends up on a British boat bound for Virginia. And the inclusion of elements from Jefferson's personal life add much: not only was he dealing with the collapse of the state he governed, but also with an ailing wife and a dying child.
The story of the flight itself is followed by a good treatment of the aftermath, in which Jefferson was strongly criticized for his actions at various later points, and felt compelled to depend himself vociferously and at great length. Kranish's closing episode of the book, which features Henry Lee visiting Monticello just six days before Jefferson's death to view papers pertaining to the period of the escape in 1781, makes the case quite clearly that this was an episode that had a major impact on Jefferson's life and reputation.