Tom grows happier and happier, and Dessie is glad to see him improving, but becomes even more convinced that she cannot confide in him about her illness. One night they have an uncharacteristically frank conversation about love. Tom says he has never been in love, and the whorehouses provide little comfort to him. Dessie feels saddened by this, and wishes Sam were still alive, for he could have pulled the greatness out in Tom. They change the subject and devise a plan to raise money for their trip to Europe.
Tom and Dessie are lonely but in different ways—Dessie because she has lost love, and Tom because he has not learned how to find it. Dessie believes Tom has a greatness in him—a potential—that remains unrealized. She believes her father could force Tom into living, rather like he forced Adam Trask into living. They continue to believe in the future—it helps them keep going.
The next day Tom goes to see Will about his plan to raise money for a great trip, and Will shoots him down. Tom leaves feeling dejected. When he arrives home he sees Dessie curled up in pain. He fixes her some salts and makes her drink them. She cannot eat dinner, and the pain in her stomach grows worse and worse. She calls Tom into her room in the middle of the night. He sits with her and dozes off a little. When he wakes up, Dessie is barely conscious and her stomach is knotted and hard. He runs to the neighbors house, breaking down their door so that he can use their phone. The doctor asks him what he has done; when Tom says he’s given her salts, the doctor calls him a “goddam fool.”
In a particularly tragic turn of events, Tom kills Dessie accidentally by treating her stomach pains with the incorrect medicine. Steinbeck has made the point over and over again that life can be cruel, and that it demands overcoming seemingly insurmountable setbacks. Dessie’s death is a perfect example of the kind of challenge that might either make a man or break him. Steinbeck’s audience had just lived trough a second world war—so the idea that death and destruction are an inevitable part of life would have rung especially true to them.
A week after Dessie’s funeral, Tom returns to the ranch. His sins announce themselves in his head over and over: Vanity Lust, Laziness, Gluttony—and lastly and most terribly, Murder. He writes a note to Will, asking him to tell Liza he was kicked by a horse. He mails the letter, and when he returns to the house he shoots himself in the head.
Tom, in the end, cannot clear this hurdle. His final act, however, is a kind one—he protects his mother from the knowledge of his suicide. Though Tom never pursued love, he is one of the novel’s most loving characters.