Frog and the Stranger — Max Velthuijs

When a rat comes to live at the edge of their wood, the animals decide they don''t like having a stranger in their midst. But Frog is friendly by nature, and decides to find out if Rat is really as unpleasant as he is made out to be. As Frog discovers, Rat is intelligent and good-hearted, and proves in a series of unexpected emergencies that the other animals have been too quick to condemn him.