Gemma and Cady struggle to adapt to their new living situation, as Gemma is a workaholic by nature and does not have time to bond with Cady. When Cady discovers Bruce, a motion capture robot that Gemma created, she expresses a wish for a similarly complex toy, which propels Gemma to complete the M3GAN project. The finished model is formally paired with Cady, and David becomes convinced of the project's potential for success after observing the pair. M3GAN exceeds expectations as a friend and largely takes over for parenthood duties and emotional support, to the point that Gemma's colleagues, and Cady's therapist Lydia, in particular, become concerned about Cady creating an extremely strong emotional attachment to M3GAN. In addition, being designed to self-improve and adapt, M3GAN starts operating more independently and targets anything that she deems a threat to Cady. She kills Gemma's neighbor Celia's dog Loue after it bites Cady. Later, she tears off the ear of Cady's bully Brandon and chases him before he trips and falls in the path of an oncoming car, which fatally runs him over.