Our story starts 200 years before Kal-El's birth, with Seg-El, Superman's grandfather, recounting the story of how Superman came to be. Back then, Seg's grandfather and master scientist, Val-El, was executed for treason after refusing to pledge allegiance to overlord Rao, a new, dictatorial power, and for not retracting his warning that a foreign life-force is coming to destroy Krytpon. The El family was stripped of its rank. Fast-forward about ten years. Seg is grown up, fine looking, and on his way to Kandor to give his father. who works as a footman there some medicine. He intercepts an assassination attempt (by tackling the assassin). He's reward for his heroism by Daron-Vex, the man who presided over the execution of Val, who gives him his daughter Nissa's hand in marriage and a spot in the science guild.
On his way home, Seg is intercepted by a guy named Adam Strange. Adam is from Earth, and traveled many light years to get to Krypton to warn Seg someone from the future is coming to Krypton to make sure Superman is never born. Adam also gives Seg a piece of Sandstone with the Superman insignia on it, and tells him to find the Fortress. When Seg's mom gets a look at it, she steals a government airplane and flies it to the... Fortress of Solitude, Val-El's workstation! But then government forces, called Sagitari, swoop in and arrest Seg's mom. She, and her husband, are charged with sedition, and executed by shooting. Feeling pretty solitary after the death of his parents, Seg returns to the Fortress of Solitude, where he's met by Adam again. This time, Strange has brought a cape: it's meant to signal to them how much time they have left before they run out of time to save Superman. When that happens, there will be nothing to stop Brainiac from consuming Krypton… and every other planet in the UNIVERSE! Well, Seg's ready to give it a try.