Wearing pajamas, a man with Neanderthal features stumbles through the Arizona desert. He falls and dies. Dr. Matt Hastings, a bright, handsome and sympathetic doctor from the town of Desert Rock, is called to view the body. Asked to give an opinion as to cause of death, he finds himself perplexed. Hastings learns that Deemer and Jacobs have been conducting experiments on animals in an effort to use an atomic isotope to create a super food nutrient. Yet, the nutrient has not been perfected. Other animals have died after receiving injections, and still others have kept growing to gargantuan proportions. The latter include a white mouse, a guinea pig, and a Mexican red rumped tarantula.

"Itsy Bitsy Spider" is a popular nursery rhyme that describes the adventures of a spider as it ascends, descends, and re-ascends the downspout or "waterspout" of a gutter system.
The Itsy Bitsy Spider climbed up the water spout.
Down came the rain, and washed the spider out.
Out came the sun, and dried up all the rain;
And then Itsy Bitsy Spider climbed up the spout again.