Professor Utonium and his son Ken are assigned to study Chemical X (a mysterious substance which mutates into Chemical Z when buns are dropped in it). Mysteriously, a glacier appears in Tokyo Bay. Ken attempts to use Chemical Z to destroy it but instead, it causes strange, black and white rays of light to slice through the city. When the black rays hit objects, people and animals the rays transform them into monsters. When the white rays hit three young girls, they are given superpowers and become a force for good called Powerpuff Z.