Big cat is the tiger who came to tea for the 21st century. Except in this case, the tiger doesn't just come to tea, he comes for breakfast, lunch and dinner too - in fact he moves in! Isobel's grandma has lost her glasses and she can't see a thing without them. While Isobel and Gran are in the garden searching for the specs, they come across a cat. A very big cat. A very big and friendly cat. The big cat moves in with them, much to the disgust of all gran's other cats. He might be good fun, but he takes up lots of space and eats every scrap of food. Eventually the new cat's mum and dad turn up, looking for their missing son. And they just happen to have found gran's glasses too. The tiger family are delighted to be reunited - and gran now sees that she's been sharing her house with a tiger!