Kevin J Anderson & Brian Herbert 
Sandworms of Dune [EPUB ebook] 

As the no-ship Ithaca flees through space, the heroes of HUNTERS OF DUNE finally meet the Enemy who followed the violent fanatics, the Honored Matres, back to their universe. The thinking machines vanquished by Serena Butler’s jihad were not destroyed, only driven into exile — and now, tens of thousands of years later, they are back. Can the resurrected heroes on board the Ithaca save our race from annihilation?