For thousands of years, man has been evolution's greatest creation... until now.

A brilliant scientist, Dr. Susan Tyler and her husband, Dr. Peter Mann, Deputy Director, Centre for Disease Control, team up in New York City where, to all appearances, they successfully eradicate an epidemic threatening the lives of scores of children.

Dr. Tyler recombines the DNA of various species to create a biological counteragent to the carrier of the disease. She calls this new species the Judas breed and with the Dr. Mann's assistance introduces it into the bio-system on New York city.

Three years later their cure has come back to haunt them with a vengeance. Their cure has taken on a life of it's own. They've altered the balance of nature, and nature is striking back!