“Other Mommy” is a horror movie starring Jessica Chastain as Ursula, Jay Duplass as her husband, Russell, and Arabella Olivia Clark as their daughter, Bela. A demon that mimics Ursula targets Bela and repeatedly asks the little girl to let it into her heart. The film adapts Josh Malerman’s 2024 novel “Incidents Around the House.”
Warning: major spoilers for the movie and book endings ahead.
In the movie, Bela defeats Other Mommy by continuing to refuse its request to enter her heart. Bela and both parents survive, though the ending hints that she’ll remain uneasy around Ursula.
In the novel, the figure Bela recognizes as Grandma Ruth is Other Mommy in disguise. The demon has killed Ruth and uses her appearance to lure Russell and Ursula to their deaths, leaving Bela alone and willing to let it into her heart.
While the movie leaves Bela alive with her parents, the book ends with the demon occupying her body and Bela trapped in the purgatory it came from.
