"The Feast of Roses" by Indu Sundaresan. As it seems with most sequels, the first book was better. Although, it was just as intriguing as "The Twentieth Wife". I was a bit distracted in how the author would give background explanations to the reader who hadn't read the first book. So I would just skim through those.
If you have read the first book and want to find out what happens to Mehrunnisa in her reign as Empress of the Mughal Dynasty, then read on! The author did an outstanding job of sharing the many details of Indian history, culture, and customs. I liked the character, Mehrunnisa in the first book, but then found it waning as her thirst for power increased.
Here are some previous postings for the first book,
"The Twentieth Wife":