Shipwreck survivors found on the presumably uninhabited Infant Island leads to a scientific expedition that discovers a surviving native population along with the Shobijin, tiny twin fairy priestesses of the island's mythical deity called Mothra. After the fairies are kidnapped by an exploitative businessman named Clark Nelson, Mothra sets out to rescue them.
When a narcotics deal goes sour and a suspect disappears, leaving only his clothes, Tokyo police question his wife and stake out the nightclub where she works.
When a rare species of butterfly is found in a mysterious valley in Japan, a pair of entomologists go to investigate and find more. They discover Varan, a giant monster, who decides to leave the valley and head straight for Tokyo.
A failed science experiment gives a librarian the ability to turn into a gaseous substance. He goes on to rob banks to fund his dancer girlfriend's career, killing those who interfere. Now Tokyo's most wanted criminal, can authorities stop him?
