George and Lennie make camp on their way to a new ranch. They discuss the past and their dreams and plans if things go wrong at the ranch. Lennie tells George to tell him the dream which is where he is most happy.
Candy shows them around, we meet the boss who is suspicious of George stealing Lennie's money. Curley threatens Lennie. Curley's wife then flirts with Lennie. Slim mentions his pups and Lennie wants one. Carlson discusses killing Candy's dog.
Slim has given Lennie a pup. George and Slim discuss Lennie over cards. George tells Slim about Weed. Whit finds a letter in a magazine. Carlson shoots Candy's dog. George and Lennie talk about the dream and Candy joins. Lennie then breaks Curley's hand.
Crooks talks to Lennie about himself and the land. Candy joins in, Crooks asks to come in on the dream farm. Curley's wife arrives and argues with them, threatening Crooks. George comes in and they leave. Crooks then backs out of the plan.
Lennie has killed his puppy because he gets too attached and smothers it. Lennie and Curley's wife talk about her promised life as a Hollywood actress. After playing with her hair, he breaks her neck and runs away. When Candy finds her he tells George, then Curley finds out and wants to kill Lennie.
Lennie is waiting in the clearing and see's visions of the dream. George arrives and shoots Lennie while telling him about the dream farm. Soon the other men arrive.