In science class at Midvale Orphanage, Supergirl gets the idea that somewhere in the universe, there may be a planet like Earth containing a double of every person, including Supergirl. She asks Superman for help to find such a planet. Superman plugs data into his Super-Univac computer and discovers the planet Terra, which orbits the star Sun-X45-266. Supergirl hopes to go there, where she may openly reveal her existence, so that she can prove to Superman she's ready to be revealed to the people of Earth.