The second fantastic book in this series about four friends who want to make the world a better place.

Izzy and Willow are being taken for a walk along the river by Emily's boisterous dog, Billy, when he decides to chase after a water-rat. Both animals land in the river, which is so choked with rubbish that Billy can't get out. His paw is stuck in an old bike wheel and the girls must work to free him. The adventure gives Izzy a great idea for their next project, though, and it's a very very muddy one...

A brilliant series about the small changes that make a big difference from bestselling author Holly Webb.

With cover illustration by Owen Gildersleeve.