The novel begins with George Milton and Lennie Small, two itinerant farm workers, traveling to a new ranch in California after fleeing from a previous job due to an incident involving Lennie. George, a small but intelligent man, looks after Lennie, a physically strong but mentally disabled man who does not understand his own strength. Despite their hardships, they share a deep bond and a shared dream: to one day own a small farm where Lennie can tend to rabbits.

At the ranch, they encounter various characters, including Curley, the aggressive son of the boss; Curley’s wife, a lonely woman seeking attention; Slim, a respected and kind worker; and Candy, an aging ranch hand who hopes to join George and Lennie in their dream. As they work toward saving enough money, tensions rise when Curley’s wife takes an interest in Lennie, whose lack of understanding of social norms makes him vulnerable to trouble.

One day, Lennie accidentally kills a puppy in the barn, distressed by his inability to control his strength. Curley’s wife finds him and, seeking companionship, allows Lennie to touch her hair. When she panics, Lennie unintentionally kills her in his attempt to silence her. Realizing the gravity of what he has done, Lennie flees to a hiding spot George had designated earlier.

The men at the ranch, led by Curley, form a mob to hunt Lennie down. George, understanding that Lennie will face a brutal fate at their hands, makes the heartbreaking decision to find Lennie first. He comforts Lennie by speaking of their dream one last time before mercifully shooting him in the back of the head.

As the novel closes, George is left alone, burdened by the loss of his closest friend and the crushing reality of their unattainable dream. Of Mice and Men is a powerful tale of companionship and sacrifice, underscoring the difficulties faced by those living on the margins of society during the Great Depression.