With his assistant, young Rufus Ockford, from Winnemac, Martin tries to clean up Nautilus and free it from rats, fleas, and disease. He has time again for laboratory work and is happy. Then a storm breaks.
Martin and Ockford head a gang which invade and tear down unsanitary tenement houses belonging to Mrs. McCandless. At first, the reaction of the influential Tredgold set is favorable, but later their attitude changes when Martin refuses to leave his laboratory to join in a Saturday night frolic.
Opposition to Martin develops on all sides at once. He blames himself again, feeling that he is a failure. His salary is cut again to the point that he is practically forced to resign or starve. He gets in touch with Angus Duer in Chicago.
Duer, now a highly successful surgeon with Rouncefield Clinic in Chicago, offers Martin a salary of twenty-five hundred dollars a year instead of four thousand, previously mentioned. Martin accepts. Pickerbaugh writes a letter from Washington indicating that he is disappointed in Arrowsmith. Martin vows that he is "licked" again and that he is through from now on with everything but moneymaking.
Again the conscientious but hard-headed Arrowsmith is the victim of forces too strong for him and is practically driven from his position in Nautilus. Refusing to become a playboy with the Tredgold set, he loses their friendship and influence. The mayor, the Parents' and Teachers' Association, and all the fashionable churches turn against him. Klopchuk and F. X. Jordan label him as crooked. Even Pickerbaugh repudiates him.
Once more Lewis uses Martin's unpopularity as a seeker of truth as a device for bringing about a change of scene, this time from Nautilus to Chicago.