Grandmas from Mars (Broché)

Fred and NelI's parents are off to a meeting. But first they tell Grandma, "Here's what they'II be eating. It's school in the morning, they can't be up Iate. So : homework, a bath - and in bed before eight." But, HANG ON, there's something not quite right about Fred and Nell's grandma. In fact, she's acting very strangely indeed. And is that a spare eyeball ? A tail ? A striped tongue ? That's NOT their grandma, it's an ALIEN ...