Homer Bannon, the old cattleman in Horseman, Pass By, owns a ranch a few miles south of Thalia, Texas. In his eighties, he has spent his life building a cattle herd of exceptional quality. He is a prosperous rancher, whose joy comes in riding over his land among his cattle. Most of his affection goes to his land, not to his nagging second wife, Jewel, or to her son, Scott “Hud” Bannon. He loves his seventeen-year-old grandson, Lonnie, and tries to pass on to him his feeling for the land and for the traditions of the cowboy past.

Hud Bannon is the best and most reckless cowboy in Texas when he wants to be, Lonnie says, but the thirty-five-year-old Hud spends more time boozing and chasing wild women than working cattle. Hud values the land only for the money it can produce: He wants oil wells on the land, not cattle. Homer’s resistance to having holes punched in the land by oil rigs seems to Hud to be mere senility.

Seventeen-year-old Lonnie is narrator of the story. He loves and respects his grandfather, but Homer’s stories of the old ranching days can no longer satisfy the lonely and restless boy. At night, after everyone has gone to bed, Lonnie often climbs to the top of the windmill and sits, looking off at the lights of Thalia and Wichita Falls. The future confuses Lonnie. Neither Homer’s traditional values nor Hud’s materialism seems adequate. Even in love there is confusion. Halmea, the black cook, a strong, wise woman, understands Lonnie’s loneliness and his sexual needs, but there is very little that an older, black woman, half sexual object and half mother-surrogate, can do for a young white boy living in Texas in 1954.

The action of the novel starts when one of Homer’s cows dies. The state veterinarian tests the herd and finds it infected with the dreaded hoof-and-mouth disease. Homer’s entire prize herd will have to be quarantined, then killed and buried. Before the results of the tests come back, a key conflict occurs. Hud wants to sell the herd before it is quarantined. Homer refuses to pass his problem along to some unsuspecting rancher. To Hud, Homer’s moral uprightness is a sign of senility. Another defining conflict comes when the state veterinarian gives Homer the bad news and tries to ease the blow by telling him that he can sell some oil leases while he is waiting to rebuild his herd. Homer says:If there’s oil down there these boys can get it sucked up after I’m under there with it. . . . I don’t like it an’ I don’t aim to have it. I guess I’m a queer, contrary old bastard, but there’ll be no holes punched in this land while I’m here. . . . What good’s oil to me. . . . What can I do with . . . [oil wells]? I can’t ride out ever day an’ prowl amongst ’em, like I can my cattle. . . . I can’t feel a smidgen a pride in ’em, cause they ain’t none a my doin.

Homer’s attitude toward oil confirms Hud’s view that the old man is disintegrating, and Hud plots to take the ranch away.

With the herd slaughtered and buried in huge pits, Homer is physically and mentally exhausted. Hud explodes in frustration, raping Halmea, while Lonnie, beaten, watches. The climax comes when Homer falls and hurts himself. Hud and Lonnie find him writhing in pain. Lonnie goes for help. When he returns, he finds that Hud has shot and killed Homer. Did he shoot Homer to take the ranch or did he, in a flicker of love that he had once felt for the old man, kill him to stop his suffering? Lonnie does not know.

At the funeral, Lonnie feels reconciled to Homer’s death, knowing that his grandfather is going back into the land he loved. He leaves the ranch, knowing that neither Homer nor Hud has left him a usable past. Perhaps he will become a wanderer, like so many of McMurtry’s displaced characters.