Amy Adams really does throw herself into this as mother to a young lad whom she looks after whilst her husband (Scoot McNairy) goes to work - frequently for many nights at a time. There's no suggestion of infidelity, but gradually she begins to feel the strains of this relentless young lad's activities. He rarely wants to sleep, is always full of beans and has a penchant for repeating the odd expletive at exactly the wrong time! It's when she starts to notice some unwanted bodily hair, then some seemingly enlarged incisors that she begins to worry if she isn't undergoing some sort of transform...