What is Chapter 1 of Of Mice and Men about?

This is the chapter where the main characters are introduced: George and Lennie. George looks after Lennie who is mentally disabled. They are both nearing middle age.

Lennie, who is confused, asks George where they are going. (Clearly, Lennie is mentally disabled.) George becomes angry that Lennie has already forgotten their plans. Lennie apologizes, and George softens. Lennie says he remembers the rabbits, which is the only part of their plan that he ever remembers. George says that he is carrying Lennie's work card so it does not get lost. As they talk, George notices Lennie has something in his pocket. It is a dead mouse that he has been petting as they walk. George takes the mouse from Lennie and throws it away. Lennie again says he has forgotten what they are doing. George explains that they are going to work on a ranch. He tells Lennie not to speak when they meet their new boss. He makes Lennie repeat it a few times in an attempt to help remember.They talk about how they had to run away from trouble at their last job in Weed. George says Lennie creates many problems, and he talks about how easy it would be if he were on his own. Lennie wants to go the ranch to eat, but George says they will spend the night outside by the river.The men eat cans of beans by the fire. George reminds Lennie once again not to say anything to their new boss. He then tells Lennie to look around and remember the place where they are sitting. George tells Lennie that if he gets in trouble, he should run to this place and hide in the brush.