Echoes of Krypton is the first chapter of The Last Son, Book One: Gatherings.
Following the trial and banishment of General Zod to the Phantom Zone, scientist Jor-El finds that the planet Krypton is about to explode and is unable to convince the populace of his theory. He and his wife sen their infant son to Earth. There, he is found and raised by Jonathan and Martha Kent.
Years ago, on the planet of Krypton, its inhabitants went to war against the Shi'ar Empire that entered their galaxy and invaded their planet. Within 6 years, the Kryptonians repelled the Shi'ar through their powerful technology and thanks to the efforts of General Dru-Zod, the head of the Kryptonian Defense Force, who broke the siege aided by the new weaponry developed by Krypton's most brilliant scientist, Jor-El, Zod's longtime friend. With the Shi'ar defeated, the Shi'ar Emperor, Kral'Nor, was overthrown and exiled by a group of Shi'ar that opposed the war and the expansion, led by another of the Imperial Family. The New Shi'ar Empire quickly negotiated for peace, ending the war.
However, in his campaign, General Zod is accused of war crimes of destroying Shi'ar warships that were about to surrender. Judged by Krypton's Council of Twelve, of which Jor-El was a part of, Zod justified his actions were necessary to defending their planet through absolute force and doesn't show any remorse for his actions. Jof-El, despite trying to reason with his friend and shocked by his newfound aggression, agreed with the Council's verdict of banishing Zod to the Phantom Zone.
Thereafter, Jor-El shares his findings with the Council, which concerns of unusual tectonic shiftis in their atmosphere, insisting that Krypton will soon explode. However, the Council is skeptical and turn to Brainiac, Krypton's omniscient central computer created by Jor-El, who dismisses Jor-El's findings and explains that Krypton is only undergoing a planetary shift.
In spite of Brainiac, Jor-El still believes he's right. He goes to Brainiac's central unit and discovers that he's correct, and Brainiac knows it. Brainiac lied so that he could secretly download himself into a satellite,