Jessica Chastain Reveals the ‘Painful’ Secret to her Terrifying Smile in Other Mommy

Jessica Chastain explained how she pulled off the terrifying facial expression she makes in the Other Mommy, saying that physical “pain” was a central part of getting her uncanny smile just right.

Chastain stars in Universal Pictures’ Other Mommy, where she plays both the mother of a young girl and the entity that haunts her family. It’s a Coraline-style premise that adds another horror film to her steadily-growing roster of projects in the genre (IT Chapter 2, Mama, Crimson Peak).

The big draw for this film is Chastain’s horrifying transformation from a caring mother to a bloodthirsty entity wearing her skin. Trailers for the movie show the acclaimed actress in both roles; when she plays the entity, she wears a dead-eyed expression with a wide, almost painful-looking smile.

It turns out that this smile does, indeed, channel some element of physical pain, as told by Chastain during an appearance on Jimmy Kimmel Live where she explained how she came up …