Fujiko is taken hostage in exchange for the world's largest ruby, which Lupin recently acquired from the royal house of India. The one making the demand is Fantoma Mark III, grandson of the mysterious European master thief and disguise artist, Fantoma. He intends to use the ruby as the oscillation unit of a laser satellite, with which he will melt the Antarctic ice, thus sinking the world's major cities, and enabling him to conquer the world. Lupin's attitude is, how dare you think of using my ruby and Fujiko for something like that! Can Lupin figure out how to swim in space?