When Billy left his pet spider, Helen, at the Zoo, the animals suddenly became happy and contented. The lions snoozed all day long, the elephants enjoyed their baths, and the zebras ate their hay in peace -- all because Helen was spinning webs and catching flies.But one day Helen's webs were swept away. The Keeper had the cages cleaned for the Mayor's inspection tour. Soon the flies were back again and the animals were miserable once more. But not...