Three children combine super-powers to become the super hero Sigma and battle an evil alien sorceress.

An alien scientist escapes from his planet and finds his way to Earth. However, he is followed by the evil Joanna and her gang. On Earth, Joanna discovers a girl, Mira, who naturally emits powerful radio waves. Her efforts to capture the child leave Mira paralyzed and her friends Jong-hun and Dong-hyeok turn to the scientist for help. He is touched by their friendship and endows the children with superhuman powers which they use against Joanna and her thugs—Anonymous