Book three of the prelude to the original Dune series answers many questions, but also leaves some unanswered, which is good. Brian Herbert and Kevin Anderson, to be honest to the Duneverse could not try to explain it all away, that is one of the many features of the Original Dune novels by Frank Herbert that keeps the reader intrigued, and makes the the books more adventuresome, the philosophy is within the reader.
In this book the Emperor of the known Universe, Shaddam IV has devised a plan with his right hand man Hasimir Fenrig, to create a synthetic form of the Spice Melange. In doing so he will hold even more power over the universe. As you may know, the Spice extends life, and makes space travel possible and is only found on one planet, Dune (Arrakis).
On the machine planet, Ix,Tleilaxu "scientists" use slaves and prisoners as part of a horrific plan to manufacture a synthetic form of melange known as amal. If amal can replace the spice from Dune, it will give Shaddam what he seeks: absolute power. However the amal is not quite right. Adjudica the Tleilaxu that has created the amal, has not run adequate testing but has been taking the amal and has been dosing the Sardukar guards with the amal and gains some control over the Emperor's terror guards. Also we learn how the Tleilaxu use women to become living tanks to produce the amal, thus explaining why there are no Tleilaxu women.
Duke Leto Atriedes, grief-stricken yet unbowed by the tragic death of his son Victor, in an assassination attempt is determined to restore the honor and prestige of his House, has his own plans for Ix. He will free the Ixians from their oppressive conquerors and restore his friend Prince Rhombur, injured scion of the disgraced House Vernius, to his rightful place as Ixian ruler. In doing so Leto leaves his home planet of Caladan unguarded. Hearing of this and in order to save face The Beast Rabban (Harkkonen), attempts to conquer Caladan, but the master of assassins and Mentat to House Atriedes, Thufir Howat devises a plan to keep any attackers at bay.
Meanwhile, Duke Leto's concubine, the Lady Jessica, obeying the orders of her superiors in the Bene Gesserit Sisterhood, has conceived a child that the Sisterhood intends to be the penultimate step in the creation of an all-powerful being. Yet what the Sisterhood doesn't know is that the child Jessica is carrying is not the girl they are expecting, but a boy. Jessica's act of disobedience is an act of love -- her attempt to provide her Duke with a male heir to House Atreides -- but an act that, when discovered, could kill both mother and baby. Learning of the heir to house Atreides, House Harkkonen's mentat, Pitor Dufries attempts to kidnap the baby.
Like the Bene Gesserit, Shaddam Corrino is also concerned with making a plan for the future -- securing his legacy. Blinded by his need for power, the Emperor will launch a plot against Dune, the only natural source of true spice. If he succeeds, his madness will result in a cataclysmic tragedy not even he foresees: the end of space travel, the Imperium, and civilization itself. With Duke Leto and other renegades and revolutionaries fighting to stem the tide of darkness that threatens to engulf their universe, the stage is set for a showdown unlike any seen before.
This book has a great storytelling and a great culmination of many battles that as you come to the end you won't want to put it down.