To set the scene: Epitaph is book 12 in the 14-book Plantagenet Saga. I've read this saga in order: no dipping in and out, no random reading of certain titles because I'm more interested in them than in other titles. The saga starts with Eleanor of Aquitane who marries Henry II of England, and follows all the way through to Richard III in The Sun in Splendour.
Epitaph is set in the reign of Henry VI, the baby King. I'm not sure who I expected the "three women" of the title to be, but I was a little surprised that they were Katherine, the Dowager Queen of England; Joan of Arc; and Eleanor, Duchess of Gloucester. It actually makes sense that it's these three: all of them have roles in Shakespearean plays, making them better known that most women of the historical period. And as I said, I don't know who I was expecting the three women to be, given that Margaret of Anjou clearly gets the whole next book in the series, Red Rose of Anjou, to herself.
The book is divided into three parts, one named for each of the women, however the story of each part is not limited to the namesake; I'm still in the first part, but Eleanor Cobham who will become Duchess of Gloucester, has already appeared (and become the mistress of the Duke of Gloucester).
I'm finding the romance of the Dowager Queen and Owen Tudor awkward to read. There's a separate book in the Queen's of England series about Katherine of France: it will be interesting to see if that's a separate story or really just a re-working of what she'd (I think) already written in this. (I'm too lazy to check the publication dates right now.)
So those are my early thoughts on Epitaph.