When Boot catches sight of a robot pet it used to know - Mr Piggles - our hero and pals follow it to a beautiful green square in the city of skyscrapers.

Here they find not just real nature, but also a haven for broken and rejected pets. They also meet the children who look after the pets, and for whom this green space is a sanctuary too. But Boot is distracted by its emotions, swinging from happy to sad ... maybe Boot is broken? Can it work out what is wrong, with the help of its friends?