"This time could you try it sweet and modest, but also hot. And can you be younger?" requests Fallon, who plays a Hollywood film director in the sketch.
In the "every audition ever" skit performed Friday on "The Tonight Show," Chastain attends a makeshift casting call to read for the movie's role of Angela. She's prompted by Fallon -- who plays the film's off-camera director -- to read one simple line: "Hi, my name is Angela. It's nice to meet you."
"That's great, but can you try it again, but hot?" Fallon asks. Chastain complies.
"Great. This time could you try it sweet and modest, but also hot. And can you be younger?" Fallon requests. Again, Chastain complies.
"Now try it like you're a spicy little peppermint with a secret, but hot," Fallon continues. "OK, little less hot this time, more sexy. Now like a strong girl boss, but pouting, but also sweet, but also you love him. But hot, you know? Just like that, but also be Wonder Woman."
"Try it like you're smart, accomplished and empowered," Fallon says to a relieved Chastain who responds, "Really? Oh, that's great."
"Sorry," Fallon interrupts. "Misread my notes there. Try it hot."
After the sketch, Chastain sat down with Fallon to talk about the sexual harassment problem that's been plaguing Hollywood for decades.
"I feel it's our responsibility to to whatever we can to amplify the voices of the people who have come forward," she said. "Because just tweeting or talking about is nothing compared to the bravery of a woman or man who's risked their career, their livelihood, everything to come forward. And the only reason they do that is to protect other people from abuse."
"So for me, silence is complicity, and I want to do whatever I can to help heal our industry, but not only our industry -- it's in many, many industries," she continued.
Chastain revealed to Fallon she's received backlash since coming forward and standing in solidarity with those who have accused some of Hollywood's most powerful men of sexual misconduct, saying she received an email from a male actor who told her she was using her platform "a little irresponsibly."
"I just feel like these people who have come forward have faced so much victimization, and I want to create a society where they're not further victimized from coming forward," she said. "I want to protect them."