A friend of mine was reading this the other day and of course I grabbed it – well, I let her finish reading it first – because I saw at once that not only was it a new Dune story I hadn't come across before but that it was filling the last great gap in the Dune prequel sequence: the gap between the three "Legends of Dune" books (The Butlerian Jihad, The Machine Crusade and The Battle of Corrin) and the "Prelude to Dune" trilogy (House Atreides, House Harkonnen and House Corrino): how did the situation at the end of the Battle of Corrin give rise to the very different situation which marks the opening of House Atreides?
This book, Sisterhood of Dune, goes halfway to answering the question. Don't be put off. It is another great story (or rather cluster of stories) and essential reading for all those Dune addicts who, like me, can't get enough of it. There is a whole new cast of authentic Dune universe characters, most of whom you either love or hate and several I identified with immediately; but, as I say, while it does show in exquisite detail how things developed following the defeat of Erasmus and Omnius and the "thinking machines", it does not bring us up to speed with the world in which Baron Vladimir Harkonnen holds Arrakis and Duke Paulus Atreides, father of Leto and grandfather of Paul, holds Caladan. And, despite the title, the Sisterhood never go anywhere near nor indeed have any connection (yet) with the desert world known as Arrakis or Dune.
I have just discovered that another book, Mentats of Dune, came out earlier this year. Please, let it be the direct sequel to Sisterhood of Dune. I've never been one for fan-fiction, but if it isn't, I shall start writing that sequel myself!