Diana has called Hippolyta and an Amazonian technician team to the moon to inspect the statue left after she apparently defeated the Empress of the Silver Snake.  As Hipployta approaches, the statue returns to life and attacks.  The Empress retreats and Hippolyta commands the Amazons not to pursue.  The Amazons return to Earth.  Diana heads to Houston to attend her next astronaut training session.   
  
During one of the sessions, the Empress uses her eye beams to attack the facility.  Diana is able to save Mike Bailey.  She departs to confront the Empress in space.  The Amazons meet her en route to the Empress. 
 
The Amazons attack.  However, they are easily defeated as the Empress fuses or destroys their bracelets.  The Empress grabs Hippolyta and threatens to remove the girdle.  The removal of Hippolyta's girdle will cause all of the Amazons to lose their powers. 
 
Wonder Woman is confused as to how the Empress knows how to defeat the Amazons so easily.  Hippolyta finally acknowledges that the Empress is in fact her sister Diana.  Diana had been killed by Hercules.  However, her spirit floated through space until she encountered an asteroid of pulsating gold and silver.  The asteroid allowed her to regain solid form.   
 
Her abilities allowed her to see Earth.  She saw Wonder Woman and believed her to be an evil impostor who had invaded her body.  She returned  to Earth to free her sisters from this evil.  Hippolyta explains she made Diana in her sister's image as a tribute to her lost sister.   The Empress finally realizes she died when Hercules ran her through with a sword.  She is welcomed to the afterlife by Aphrodite and Athena.