Holly Webb started writing fiction almost by accident, when she was working as an editor. She wrote her first book on trains, and had to leave it on someone's desk with a note as she was too scared to say she'd written it. Since then, she's written many, many more and usually works on the sofa, which is much more comfortable than a train. She lives near Reading with her family and a cat.

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.