The second volume in the original six, although the first volume is actually 3 books, Arakis, Muad Dib and Prophet. David Lynch was going to base Dune 2 off this volume, but it never saw the light of day. Although the first volume (with the three books, which are sometimes published separately, but are still one volume) is proclaimed one of the best science fiction ever created, the second volume, Dune Messiah, is not praised very highly usually. The reason for this is maybe because it is a much more contemplative module, without too much action, and at the end Paul Atreides, Muad Dib, dies voluntarily.
Alia, Paul's sister, has a large part in this volume, even describing her religious role and the cult she's leading in great detail, however she doesn't seem to influence the events until the very end when she orders the death of all conspirators. The "ghola' (zombie) of Duncan Idaho also has a prominent role and at the very end the becomes first resurrected zombie which actually returns his old memories and old self-awareness. The Bene Tleilax which create gholas and artificial metal eyes have a bargain for each possibility, whether Pail dies or not, Chani dies or not, and even Alia, while at the same time tryng to be the driving force of the conspiracy through the conditioning of the ghola of Duncan Idaho and the complementary dwarf Beijaz.
All of these conspiracy fall apart at the end of the book when Paul chooses death over and over again. Death for himself, death for Chani, death for Beijaz and all Tleilaxu conspiracies, while they counted on his wish to live and not be destroyed as the strongest motivating force, as it is probably for them. Paul became truly divine by consciously choosing his own death and permanent destruction, all in the manner of the Fremen where a blind person goes into a desert to die in order not to be a burden to their seich. This assured permanent loyalty of the fremen to Paul and his descendants (twins instead of just a a daugher, and the son born with full consciousness and powers), ensuring the survival of the Atreides imperial line.
I personally like this book a lot since it made a lot of sense within the universe building, but I can see why people who are mostly interested in the action sequences would be disappointed. Some people also complain about the extensive use of Islamic concepts and imagery throughout the books, but I find that to be a strength since it gives a reality to the world builidng and also originality, since Islam is very rarely used as a positive force within science fiction books. However, from what I've seen in the Villaneuve movie with Timothee and Zendaya, the Islamic world building has been reduced to a mere minimum, if at all. Sad.
