After Gemma becomes the caretaker of her orphaned niece, Cady, she gives her a specially designed robotic doll named M3GAN to help her overcome the grief of losing her parents, but M3GAN quickly spirals out of control.
After Gemma manages to create a doll that looks like a real girl, the horrifying truths of AI are soon revealed, and fears grow about what a robot girl that comes to life could do.