During the Great Depression migrant ranch worker George Milton rides a train boxcar and reminisces on the past when he and his friend Lennie Small traveled California searching for work. George is often tasked with protecting the mentally deficient but loving Lennie who doesn't realize his own strength and often causes trouble for them both.
They were forced to leave their last job when Lennie, who is obsessed with soft and beautiful things, strokes a woman's red dress and is later accused of rape. The pair moved on to another ranch in order to work towards their shared a dream of owning a farm on their own land. For his own part, Lennie wanted nothing more than to have soft rabbits on the farm that he could pet. In spite of the Depression and the whole country's financial problems, the men hoped that they could work enough and eventually save the money to buy some land and start their farm.
At Tyler Ranch, their newest post, an aged ranch hand named Candy brought their dream much closer to reality than it had ever been with his offer to go in on the farm with George and Lennie. Although they were closer than ever to achieving their goals, the dream was shattered when Lennie unintentionally made a fatal mistake. He tried to stroke the soft and lovely hair of the wife of the ranch owner's son Curley, accidentally breaking her neck and killing her when she tried to move away. Once he found out, the vindictive and cruel Curley rounded up and led a lynch mob to try and kill the gentle giant.
During this horrible turn of events Lennie came to the depressing realization that the farm was only a pipe dream and that he would never know anything more than the lonely life of a migrant worker. Wishing to save Lennie from a horrible and painful death at the hands of Curley, George took him out away from the ranch and the mob and told him again the story he loved best about the rabbits they would have on their farm someday. With that last happy thought on Lennie's mind George shot his friend in the back of the head to allow him a peaceful death. Back in the boxcar George thinks on one last memory, one of working happily with Lennie in the fields and then walking away with him into the sunset.