Naomi Armitage and Ross Sylibus have changed their names and live with their daughter Yoko as a happy and normal family on Mars — until an android riot breaks out at an anti-matter plant on Earth.

Armitage learns the riot is actually part of a conspiracy to suppress evidence of illegal research and development of more Third Types — androids almost indistinguishable from humans. She decides to go to Earth to find out who is behind this heinous act and encounters the most dreaded enemy yet — replicas of herself!