Animal Haven is a temporary home for all sorts of Australian wildlife, although there are a few permanent residents as well, like Oscar the owl, Fur Bag the possum, Cinnamon the koala and Alice the labrador. Meg and Mike live there, too, and they work so hard to help their parents rescue and look after the animals that the locals at Jeff's Creek have nicknamed them the Aussie Angels.
Old Ben the hermit has lived in the Otway Ranges ever since he left school at twelve. He's never married and keeps to himself - although once a month he drives his old ute into town for supplies and once a year he enters his dogs in the Otway Show and always wins the dog trials.
His blue heeler Sheila is the smartest dog in the Otways, so when Old Ben goes missing, she turns to the one family she known will be able to help find him.
The Aussie Angels are baffled. If the police and Sheila can't find Ben, how could they? But when Mike is reading about the early history of the area for an assignment, he finds that there are some old caves and an underground river not far from Animal Haven. What if Old Ben has fallen down one of the air vents? Or discovered something going on that other people don't want anyone to know about?
Sheila the heeler is determined to find her master, and so are the Angels, but it involves a cold and wet journey down the underground river and that's just the beginning!
