Gappers are baseball-sized, burr-shaped orange creatures with a compulsion to creep up out of the sea and fasten themselves to goats. When a gapper attaches itself to a goat, the goat becomes unhappy and stops giving milk - when gappers get your goat it means trouble!

The town of Frip survives by selling goat milk, so the children must brush gappers off the herd eight times daily and dump them into the ocean. And when neighbours fall out with each other, the problem increases! It takes the ingenious approach of a young girl called Capable to find a solution.