Alison has never been a fan of Christmas. But with it right around the corner and her husband busily decorating their cozy Vermont home, she has no choice but to face it. Then she gets the call. Mavis, Alison's estranged mother, has been diagnosed with cancer and has only weeks to live. She wants to spend her remaining days with her daughter, son-in-law, and two granddaughters. But Alison grew up with her mother's alcoholism and violent abuse and is reluctant to unearth these traumatic memories. Still, she eventually agrees to take in Mavis, hoping that she and her mother could finally heal and have the relationship she's always dreamed of. But when mysterious and otherworldly things start happening upon Mavis's arrival, Alison begins to suspect her mother is not quite who she seems. And as the holiday festivities turn into a nightmare, she must confront just how far she is willing to go to protect her family.