The race to Kangaroo Cliff - Alexander McCall Smith

Ben and Fee MacTavish and the rest of the School Ship Tobermory crew head down under to take part in a tall ships race, but after a good start the Tobermory runs aground after it drops out to rescue a local boy, Kimba, stranded on the rocks. When the ship's dog Henry disappears, Kimba helps Ben, Fee and their friends find him. But as the trail leads them deeper into the Outback, they begin to realize that a missing dog is the least of their problems. Who are the mysterious couple claiming to be flying doctors, and why are they interested in an abandoned mine?