The most enjoyable part of any historical fiction novel is feeling as if you are there in that time period, where the characters use no 21st century slang or mannerisms, using the appropriate etiquette. Lack of research can ruin a perfectly lovely story. If you are looking for an historical fiction novel with authenticity, look no further than Philippa Gregory's The Cousins' War series.
The Lady of the Rivers is a prelude to the previous installments of the series. Readers first met Jacquetta in The White Queen, as mother of Elizabeth, a queen and a commoner. This tale begins with Jacquetta as a young woman with knowledge of healing and a mystical family history living in a dangerous time. Witchcraft was feared by rich and poor alike in this period of time and the hysteria that led to burning so many innocent women at the stake is only a few years away.
In 1433 Jacquetta has no say as she is forced to marry recently widowed John, the English Duke Bedford Regent of France. He plans to use her powers to further his ambitions but dies before he can achieve his objective. Still a teen, Jacquetta is now a wealthy widow. The king and her family choose her next spouse, but Jacquetta refuses to obey. I don't want to ruin this for those of you who have not read the other books in this series. Pick up The White Queen and The Red Queen before you begin this medieval journey.