M3GAN is a marvel of artificial intelligence, a lifelike doll that's programmed to be a child's greatest companion and a parent's greatest ally. Designed by Gemma, a brilliant roboticist, M3GAN can listen, watch, and learn as it plays the role of friend and teacher, playmate and protector. When Gemma becomes the unexpected caretaker of her eight-year-old niece, she decides to give the girl a M3GAN prototype, a decision that leads to unimaginable and terrifying consequences.