Chris and his girlfriend Rose go upstate to visit her parents for the weekend. At first, Chris reads the family’s overly accommodating behavior as nervous attempts to deal with their daughter’s interracial relationship, but as the weekend progresses, a series of increasingly disturbing discoveries lead him to a truth that he never could have imagined.

A brilliant toy company roboticist uses artificial intelligence to develop M3GAN, a life-like doll programmed to emotionally bond with her newly orphaned niece. But when the doll’s programming works too well, she becomes overprotective of her new friend with terrifying results.