In Midvale Orphanage, Supergirl laments that her adventures aren't as thrilling as Superman's because she's not allowed to reveal her existence to the world. Wanting some thrills, she uses her Super Speed to cross the time barrier into the past. There, she tames a Brontosaurus which she names Bronty, and meets a group of cave men. When their settlement is attacked by a Sea Serpent, she defeats the serpent. In memory of her heroism, the cave men leave cave paintings of the Girl of Steel. Once she crosses back into the present, Linda Lee sees the cave paintings on display in a museum during a tour with her orphanage.