Martin orders his office equipment from the New Idea Instrument and Furniture Company, whose vice-president is his former preceptor, Dr. Roscoe Geake. He rejects the recommended Tonsillectomy Outfit but includes a steel stand, a sterilizer, flasks, test tubes, and a combined examining chair and operating table. A new plate glass sign with gold lettering reads: "M. Arrowsmith, M.D." He and Leora are in ecstasies. His own surgical case, including dental forceps, he had brought from Zenith. His first office patient is Nils Krag, with an ulcerated tooth that is extracted.
A five-year-old Ford is acquired for making country calls. Leora also learns to drive it, but it is Martin who becomes the demon driver of the village.
Pete Yesta, the local druggist, is antagonized when Martin criticizes his inaccuracy in filling prescriptions. Thereafter Martin has to prepare his own medicines or obtain them from St. Paul.
After a wild race in his Ford, first to a farmhouse where a child is dying of diphtheria and then to Leopolis, twenty-four miles away, for antitoxin, Dr. Arrowsmith returns to his first desperately ill patient just before she expires. Shocked by the turn of events, he considers giving up practice of medicine, but Leora comforts and encourages him. He then visits Dr. Adam Winter, the seventy-year-old physician of Leopolis, to discuss the outcome of the case. Dr. Winter turns out to be a fee-splitter, but he exonerates Martin in the death of the child through an article in the local newspaper. The child's parents, at first antagonistic, become Martin's staunch supporters and patients.
Two physicians are satirized in this chapter: Dr. Roscoe Geake, who reappears as vice-president of an important instrument company, and Dr. Adam Winter of Leopolis, who proposes fee-splitting to Martin.
Dramatic are the events surrounding the death of the child, Mary Novak — the wild rush for antitoxin, the arrival too late, and the final admission by her parents that they had waited too long before calling the doctor. Martin's whole absorption now is saving lives, and laboratory work is pushed aside for the time being. Always the comforting figure of Leora is in the background, offsetting the effects of less agreeable people and events.