Back in Borneo, the place she grew up, Yoko Tsuno comes across some unusual occurrences. While she is visiting some temple ruins, two men come out of the jungle and track prints on the ground. Yoko hides then sees a strange machine materialising. A young girl gets out. One of the men tries to kill this girl, but Yoko saves her. The girl tells Yoko she has come from the 39th century on a mission to arrest a certain Stephen Webbs who has devoted his life to research that will give the world the 'contraction bomb', a bomb that will destroy both earth and all humanity...