Two years after M3GAN's rampage, her creator, Gemma, resorts to resurrecting her infamous creation in order to take down Amelia, the military-grade weapon who was built by a defense contractor who stole M3GAN's underlying tech.
When robotics engineer Gemma becomes the guardian of her orphaned niece, Cady, she thinks her new invention, a robotic AI, will be a good companion. However, M3GAN begins to behave in unexpected and shocking ways.