The "Mad Men" star signed on to the big screen drama to play Krissi Cates, a stripper harboring secrets about the death of the Day family, but the actress was later thrown for a loop when producers asked her to play an entirely different role on the first day of filming, reported Us magazine.
"I got there and was doing a hair and makeup test (as Krissi) and was putting on this long blonde wig, and then they said, 'Charlize and Gilles (Paquet-Brenner, the director) would like to see you on set. And I thought, 'Okay, they're not going to like the wig, I get it,'" Hendricks, 40, said.
Theron, 39, appears in the film as Libby Day, who witnessed her family being murdered when she was just eight-year-old.
Hendricks will play the mother to the younger version of Theron.