These novels are intended to "fill in the story" between Frank Herbert's early Dune novels.

Half of the story of Paul of Dune takes place between "Dune" and "Dune Messiah" as Paul's Jihad rages, Shaddam seeks to regain his throne and Princess Irulan accepts the "task of building the legend of Muad'Dib". 
She in turn chronicles Paul's early years (between the 2001 prequel Dune: House Corrino and Dune), which feature "his friendship with Duncan and Gurney and Duke Leto's War of Assassins against Grumman".
The "Winds of Dune" chronicles events between "Dune Messiah" and "Children of Dune".



Book 1 Paul of Dune
Dune ended with Paul Muad'Dib in control of the planet Dune. 
Dune Messiah, picked up the story several years later after Paul's armies had conquered the galaxy. 
What happened between Dune and Dune Messiah? How did Paul create his empire and become the Messiah?

The Muad'Dib's jihad is in full swing. 
His warrior legions march from victory to victory, but beneath the joy of victory there are dangerous undercurrents. 
Paul, like nearly every great conqueror, has enemies--those who would betray him to steal the awesome power he commands. . . .

And Paul himself begins to have doubts: Is the jihad getting out of his control? 
Has he created anarchy? 
Has he been betrayed by those he loves and trusts the most? And most of all, he wonders... 
Am I going mad?



Book 2 The Winds of Dune
The Winds of Dune begins after the events of Dune Messiah.

Paul has walked off into the sand, blind, and is presumed dead. 
Jessica and Gurney are on Caladan.
Alia is trying to hold the Imperial government together with Duncan.
Mohiam dead at the hands of Stilgar, Irulan imprisoned. 
Paul's former friend, Bronso of Ix, now seems to be leading opposition to the House of Atreides. 
Herbert and Anderson's newest book in this landmark series will concentrate on these characters as well the growing battle between Jessica, and her daughter, Alia.