What is Crooks doing when Chapter Four begins and ends? Why does John Steinbeck set up the chapter this way?

This chapter
serves as a point for all the most broken, forgotten and expendable characters to get together.
Crooks, Candy and Lenny get together and portray the weakest and most dependent parts of the
ranch. Crooks is a black ranch hand ostracized racially and handicapped with a broken back.
Candy lost his hand to his years of hard labor and is marginalized due to his advanced age.
Lenny is not right mentally and is completely dependent on those around him. Together they
nearly hatch a scheme, but as noted before, nothing will change, as the opening and closing
scenes show.