Several centuries after the death of the God Emperor the Bene Gesserit has ordered yet another Duncan Idaho ghola from the Tleilaxu.  He is to be trained by Miles Teg, a Bashar (a military leader) with Atreides genes who is loyal to the Bene Gesserit.  This Duncan is not like the others. The Sisters have specifically asked for small adaptations, and the Tleilaxu have planted something in him themselves too.  Teg'straining, his Bene Gesserit education and the special qualities make him, even as an early teenager, a remarkable pupil.  But the Sisters have to be constantly on their guard, for treason from within, for dangers from outside.  And one day the careful preparation of the emergency plans pay off, and Idaho, Teg, with Bene Gesserit Sister Lucilla have to hide from everything, for as long as it takes.

On Arrakis, or Rakis as it is known these days, the desert has returned. Not in its original state, but the open desert is again where the mighty sandworm rules, be it that they are no longer the only source of the Spice.  And one day the priests of Rakis discover a young girl who shakes their world: she commands the worms!  They listen to her!  Soon the word is spread and not only the priests, but also the Bene Gesserit ánd the Bene Tleilax come to the planet to study her. 

And we finally meet the mysterious Tleilaxu.  They have been in touch with the Honoured Matres, who have been refining their powers during the Scattering to reach the levels of what the Bene Gesserit is capable of - with one exception: their sexual powers are far beyond those of the Sisters.  On the other hand, the religious knowledge of the Sisters allows for some approach between the two forces.  As a result of that on Rakis the cooperation between Bene Gesserit and Tleilaxu goes way beyond what they ever did together in the past.

The storylines are intertwined throughout the best part of the book, in such a way that each reveals something of the other, but at the same time one keeps wondering where this will lead to.  It's only in the last chapters that the puzzles fall together, and that is really done brilliantly.  The plotting of the Tleilaxu, the careful steering of the Bene Gesserit, the arrogance of the Honoured Matres, near the end it is unclear who the winner will be, and what the struggle is even all about.  Power, supremacy, sure, but in what way?  Over whom?

This intertwining, the interaction of the main storylines, and that of the characters, make this 5th novel in the series of a quality that surpasses all but the first.  We meet interesting characters, we meet them in an interesting way.  Bashar Miles Teg is an experienced military leader called back from retirement to train Duncan Idaho.  And train he does, but not only the muscles, not only military strategies, not only fighting.  In another time, and with another education he might just as well be another Paul.  Sheeanna, the girl that commands the worms, is a delight.  For once a character shows up that is not dead serious all the time.  She really is a child, she is curious, she makes fun of the priests, she is stubborn, she wants to play, it is almost sad to see her get under the control of the Sisters.

The mixing of the storylines, combined with some surprising events that make this an anything but predictable story, and the living characters make this a most enjoyable read.  But not for those who pick this book as their entrance into the world of Dune, let that be clear.  Too much has happened, too much things that are important to understand the value of another Duncan, or who the Bene Gesserit really are.  But fans of the series will love this book.