George and Lennie are migrant farm workers who dream of owning a farm. Candy is a much older farm worker who is becoming physically feeble and terrified of not being able to keep working. He offers his life savings to help invest in a farm if he can own a share in it. Candy serves two purposes in the plot. The first is as an example of what happens to migrant farm laborers as they get older; while Candy has managed to save up a small amount of money, his wages are so low that he can't afford to retire. His other main function is his offer of his savings, which helps to keep the protagonists' dreams of farm ownership alive.
Curley's wife is an essential part of the plot. Her flirtation with Lennie arouses Lennie's irrational anger, and he kills her. As a mob is getting ready to lynch Lennie, George tries to comfort him and then shoots him to give him a painless death.