A team of scientists, led by Dr. Rick Torres (Kerwin Mathews), travels to Mexico to research radioactive material in the water. While there, they discover several octopi that appear to have a human mutation and take them back to the lab for more study. Their benign abduction awakens the parent octopus, however, endangering the lives of all the scientists. Octaman (Read Morgan), as he is called, employs several predatory methods, including strangulation and hypnosis.