The story begins when George and Lennie Prepare to arrive at the ranch to work.
George and Lennie camp in the brush by a pool, the night before they start their new job on the ranch as ranch hands.
George finds Lennie stroking a dead mouse in his pocket. He complains that caring for Lennie prevents him from living a freer life. We find out that Lennie's innocent petting of a girl's dress led them losing their lasr jobs in the weed.
However, when they talk about their dream of getting a piece of land together we know they really depend upon each other.
When George and Lennie arrive at the ranch in the morning, they are shown around by Candy.
They meet their boss and his son (Curley). George is suspicious of Curley's manner and warns Lennie to stay away from him.
They see Curley's pretty and apparently flirtatious wife and meet some of their new fellow workers, Slim and Carlson
Later that evening, George tells Slim about why he and Lennie travel together and more about what happened in Weed.
The men talk about Candy's ancient dog, which is tired and ill. Carlson shoots it and claims it to be an act of kindness.
George tells Candy about their dream of getting a piece of land and Candy eagerly offers to join them - he has capital, so they could make it happen almost immedietly.
Curley provokes Lennie into a fight which ends up with Lennie severly injuring Curley's hand.
The following night, most men on the ranch go into town to the cat house. Crooks is alone in his room when Lennie decides to join him.
They talk about the land where Crooks appears to be sceptical about it, not believing that George and Lennie are going to do what so many other men he's known have failed to do, and get land of their own. Yet when Candy happens to come in as well, Crooks is convinced and asks to be in on the plan too.
Curleys's Wife arrives. She threatens Crooks and an argument develops. Crooks realises he can never really be a part of George, Lennie and Candy's plan.
Next afternoon, Lennie accidentally kills the puppy that Slim had given him by petting it too hard which makes him sad.
Curley's Wife finds him and starts talking very openly about her feelings. She invites Lennie to stroke her soft hair, but he does it so strongly she panics and he ends up killing her too. He runs away to hide, as George had told him to do.
Candy finds the body and tells George. They tell the other men and Curley wants revenge.
Lennie hides in the brush by the pool. He dreams of his Aunt Clara and the rabbits he will tend when he and george get their land.
George finds Lennie and talks reassuringly to him about the little place they will have together then he shoots him with Carlson's gun.
When the other men find George, they assume that he shot Lennie in self defence. Only Slim understands what George did and why.