Nightbitch

An ambitious mother puts her art career on hold to stay at home with her newborn son, but the experience does not match her imagination. Two years later, she steps into the bathroom for a break from her toddler's demands, only to discover a dense patch of hair on the back of her neck. In the mirror, her canines suddenly look sharper than she remembers. Her husband, who travels for work five days a week, casually dismisses her fears from faraway hotel rooms.

As the mother's symptoms intensify, and her temptation to give into her new dog impulses peak, she struggles to keep her alter-canine-identity secret. Seeking a cure at the library, she discovers the mysterious academic tome which becomes her bible, "A Field Guide to Magical Women: A Mythical Ethnography," and meets a group of mommies involved in a multi-level-marketing scheme who may also be more than what they seem.