Tramp, the scruffy, brave mongrel is devoted to Tom. Disaster happens during a family holiday in the wilds, when Tom and Tramp get stuck underground and are threatened by rising floodwater. Tramp helps to save Tom but then slips back and is washed away by the rising water. Tom and his family, think Tramp must be dead and leave. Tramp is left all alone, a very long way from home. But he is determined to find Tom again.