God give me a quiet and relentless anger against all pretense and all pretentious work and all work left slack and unfinished.
Martin was furious, Holabird delicately relentless.
When he returned to New York he would have to call on the old man and admit to him, to those sunken relentless eyes, that he did not have complete proof of the value of the phage.
He walked all the way up to their inconsiderable hotel in the Thirties, and all the way the crowds stared at him—this slim, pale, black-eyed, beaming young man who thrust among them, halfrunning, seeing nothing yet in a blur seeing everything: gallant buildings, filthy streets, relentless traffic, soldiers of fortune, fools, pretty women, frivolous shops, windy sky.
There are no more uses of "relentless" in the book.