One of the running subplots of the book is the speculation of the traitor among the House of Atreides. In the book, Hawat sincerely suspects Jessica is the one who sells out the noble clan to the Harkonnens, leading to the ultimate downfall of the Atreides on Arrakis. The movie doesn't delve too deeply into this plot line, however. Instead, it simply reveals to the viewer Dr. Yueh's deceit. With Hawat and Gurney missing from the second half of the movie, it's a possibility they might follow up on the conspirators in Dune: Part 2.