A family purchases a home robot designed to look like a grandmum. Their neighbours immediately buy a more expensivve model as the two families always try to up the other one. Both grandmums start to "terorize" their families because they were set up to ensure the mums exercise, the kids study etc. Apart from that they start causing problems to the other family ... cut ropes with hanging clothes, pierced tires, etc. Once they get to killing each other family's pets the parents get really worried ...