When Olive and some of her year 6 friends find themselves locked overnight inside Flatpack - a new IKEA-style superstore - they quickly realise that they are not alone. A number of things hitched a ride from the forest where Flatpack sources its wood and in every dark nook, they've been multiplying... After several of the group get themselves dragged off to who knows where, Olive knows she was right all along - monsters are definitely real.