This historical novel exceeded my expectations! It is not that I had low expectations, but I borrowed it from the library based on mild thematic interest; I did not expect to be gripped and impressed by this book as much as I was.

The aftermath of the British civil war in England and the early years of the British colonies in New England make for a fascinating historical backdrop that I loved learning more about (especially since I have recently moved to Massachusetts from Europe).
Of course this is a novel, not a history textbook, but my impression is that Robert Harris does an excellent job enriching historical fact with fiction where the historical record is sparse.

My enjoyment of reading novels is usually predicated on being able to sympathise with at least one character and their cause, which on the surface was not the case in this book: I have no sympathy for the religious zealotry and (first domestic, then colonial) violence of the Puritans, nor for the corruption, suppression of political rivals and extreme brutality of the British royal regime.
It is to Harris' credit that I nonetheless found both Edward Whalley (one of the regicides) and Richard Nayler (the royal investigator going after them) sympathetic characters for much of the narrative.
(I could, however, not warm to the second regicide, William Goffe, who seems to have been a most unpleasant religious fanatic.)

I also found the ending of the narrative very well done.

All in all, a strong recommendation for enjoyers of historical fiction who want to learn more about this period in history.