The "Twilight" actress said she is very nervous about her upcoming role in the film, which also stars Nicholas Hoult of the upcoming "X-Men: Days of Future Past."
"I can't believe I agreed to do it," she said in a recent interview. "I'm terrified of it ... Though it's a movie with a really basic concept, it's overtly ambitious."
The actress describes "Equals" as an updated version of the 1956 film "1984," based on George Orwell's classic 1949 novel about rebellion in a repressed futuristic society.
"In 'Equals,' things go wrong because you can't deny the humanity in everyone," said Stewart. "It's the most devastating story."
Doremus described his sixth film as being "about love in a world where love really doesn't exist anymore." "Equals," which was written by Nathan Parker, is the first film Doremus will direct that he didn't write himself.
"I trust Drake's process and I know we will do something really natural and real," said Stewart. "But I told Drake, 'Don't expect that I am going to be able to do this. It's too hard.' But he wouldn't take 'no' for an answer. I've given directors disclaimers before, but never this much."
Jennifer Lawrence, who appeared in Doremus' 2011 film "Like Crazy," also read Parker's script, Doremus said.
"Jen and I worked together before and she was fantastic," said the director. "It's exciting to talk about the character with different people, but it became evident in my head that Nick and Kristen would have great chemistry."
"Equals" begins filming later this year.
The Associated Press contributed to this report.