Maya is a quick-witted young woman who comes over the Mexican border without papers and makes her way to the LA home of her older sister Rosa. Rosa gets Maya a job as a janitor: a non-union janitorial service has the contract, the foul-mouthed supervisor can fire workers on a whim, and the service-workers' union has assigned organizer Sam Shapiro to bring its "justice for janitors" campaign to the building. Sam finds Maya a willing listener, she's also attracted to him. Rosa resists, she has an ailing husband to consider. The workers try for public support; management intimidates workers to divide and conquer. Rosa and Maya as well as workers and management may be set to collide.

Prior to filming, Adrien Brody did undercover research as a union member in Los Angeles. He went to conventions and sat in on strike talks. A couple of the members recognized him, but Brody persuaded them not to blow his cover.