Three years ago, Abigail E. Disney began to publicly excoriate the Walt Disney Company for its “obscene” pay inequality, with Robert A. Iger, who was then chief executive, at one end of the scale and hourly theme park workers at the other. The company founded by her grandfather and great-uncle repeatedly returned fire, at one point calling her assertions a “gross and unfair exaggeration of the facts.”

But Ms. Disney has refused to back down, even though the company recently agreed to a 16 percent raise for certain theme park workers. In fact, she is escalating her campaign — and, for the first time, bringing along two of her three siblings.

“The American Dream and Other Fairy Tales,” an activist-minded documentary about the pay gap between corporate haves and have-nots, will premiere on Monday as part of the Sundance Film Festival, which is being held digitally because of the pandemic. Ms. Disney and Kathleen Hughes directed the film; Ms. Disney’s sister, Susan Disney Lord, and a brother, Tim, are among the executive producers. The movie positions the entertainment company that bears their name as “ground zero of the widening inequality in America.”

To paint that harsh picture, Ms. Disney and Ms. Hughes profile four Disneyland custodians, who, at the time of filming (prepandemic), earned $15 an hour. They all struggle mightily with soaring housing costs in Southern California. One says he knows Disneyland workers who have had to “make a decision between medication or food.”

Intermittently, the filmmakers cut to photographs of Mr. Iger, who was Disney’s chief executive from 2005 to 2020, a period of stunning gains for stockholders (including Ms. Disney and other members of her family). Viewers are reminded that Disney awarded him a pay package in 2018 worth $65.6 million. Stock awards tied to the acquisition of 21st Century Fox assets made up 40 percent.

Ms. Disney and her sister are then shown reminiscing about their grandfather, Roy O. Disney, who founded the company in 1923 with his brother, Walt. “I cannot see him taking $66 million home for a year’s work in the same year when, at the same company, people can’t afford food,” an indignant Ms. Disney says. Her sister responds, “That would never have happened — that would never have happened.”

The Disney