Ver PelisPlus. "Essential" is a documentary film that exposes the extreme economic vulnerability that income inequality has created for millions of working class Americans. Viewed through the lens of the Southwest Carpenters Union, and featuring numerous experts, the film examines how unionization in the 20th Century created the largest middle class in the history of the planet, but union demise in the 21st Century has created income inequality that is reaching levels not seen since the Great Depression.