Inciting Event: Young medical student Martin Arrowsmith meets nursing student Leora and immediately falls in love with her. He engages himself to her—and gets out of his previous engagement to another woman.

First Plot Point: In a rapid-fire patter of events, Martin leaves school (he thinks forever) after falling out with his favorite professor. He then marries Leora—against her family’s wishes—and brings her back to Zenith, so he can resume school. He then graduates to an internship.

First Pinch Point: Martin opens his own practice in Leora’s North Dakota hometown. He begins by watching a young girl die of diphtheria because he couldn’t save her in time. His practice gets started anyway, but this is the bad beginning of an ultimately doomed endeavor, as the townsfolk prove incompatible with Martin’s impatient, forward-thinking methods.

Midpoint: Martin is inspired by a medical lecturer to leave behind his small-town practice and move to the big city of Nautilus, where he goes to work as an assistant health inspector. Even though he is ultimately unhappy in this job as well, it signals the change in his outlook, as he slowly begins moving back into his true love: lab work.

Second Pinch Point: After taking over as chief health inspector, Martin makes enemies and gets himself fired. However, this turns out to be a good thing, as it presents him an opportunity to work for his old professor at an honest-to-goodness research lab in New York City.

Third Plot Point: Black plague breaks out in the East Indies—and Martin volunteers to go use his new wonder discovery “the phage” against it. Leora insists on accompanying him. This isn’t so much a low point for the protagonist, but it’s clearly a low point in general for all involved humanity, and it most definitely offers the thematic motif of death. It also prompts Martin, during the voyage, to finally evaluate his life and especially his marriage—in which he vows to be a better husband when they get back home.

Climax: Leora dies of the plague. Martin leaves the island a hero and marries the wealthy Joyce, whom he met while Leora was dying. He returns to his work, but struggles to juggle his science with his marriage.

Climactic Moment: Martin leaves Joyce to study bacteria in the woods.

Resolution: Joyce tries to woo him back, but Martin stands fast.