It's not the future dystopia of The Hunger Games, but it's not far off. Henry VIII requires an heir, and he must be rid of Ann Boleyn, and this is where it all starts going horribly wrong. Because the reader already knows how the story turns out there is a constant and oppressive suspense as one reads over all the details, and the details are rich. It doesn't feel like an historical novel, it feels like history, with all the bits thrown in that make it fun: the clothes, the plotting, the king losing touch with reality.
Maybe, because it's such a grim story, it shouldn't be so much fun to read. But it is.