Frank Herbert

Suddenly, the end of all life throughout the entire galaxy was only weeks away... Whipping Star introduces Jorj X. McKie, Saboteur Extraordinary, in an assignment which will decide the fate of the universe. Interstellar travel has linked every sentient to the insubstantial entities know as 'Calebans'. Now the last Caleban is at the point of extinction, subjected to systematic torture by the richest, most wicked woman in the Galaxy.
When it succumbs, every sentient creature will die with it. If McKie can solve the enigma of the Caleban and break its voluntary enslavement to its persecutor, he may be able to avert a universal doom. But how do you communicate with a non-sentient intangibility?