David has a big, shaggy dog - Goliath. Goliath is a softie, but as he is big, loud and hyperactive, he gives the impression he could be fierce. When Walter (Whacker) Wade arrives at school, he proves to be a bully of the worst kind - not actively stealing possessions or hurting children, but menacing and damaging other's property. It is difficult for David and his friends to do anything about the situation because Whacker is too clever. He also comes from a difficult home and has been put into a class of younger children because he has gone to so many schools. He bitterly resents this. Whacker turns pitiful when his own dog is threatened with destruction after an accident in the park, and David comes up with the answer. Afterwards Whacker becomes a more amenable character and is put in an older class. Good on the children's efforts to solve the situation themselves. Uninspiring black and white drawings; short novel.