The survivors of the lost civilization of Mu return to Earth, having fled believing the world was ending. Discovering that mankind has flourished in their centuries long absence, the collective citizens of Mu are overwhelmed by a rising hatred, born of fury and jealousy. Hal Jordan joins archaeologists Carter and Shierra Hall at an excavation site, in the South Pacific. Shierra unearths an ancient tablet, inscribed in the dead language of Mu. Suddenly, a bolt of blue lightning strikes Shierra. Though Jordan manages to throw a shield around Shierra, blunting the impact, she still loses consciousness. Hall, as the Hawkman, flies Shierra to a hospital. Aquaman, and Mera, join Jordan, who has donned his Green Lantern uniform.
Aquaman informs the Green Lantern of a trio of hot spots in the world, that may be connected to the long dead Mu empire. The Green Lantern summons the Justice League of America, then divides the teams into three, to investigate the situation. En route to California, the Green Lantern is struck down by the collective consciousness of Mu. The Emerald Gladiator is barely able to muster up enough will power to save himself. On board the Batplane, the Batman contemplates an intimate moment, shared with the Black Canary. The Black Canary tarries a little too close to the Batman, inciting a jealous outburst from the Green Arrow. The Black Canary asks the Batman for romantic advice, regarding her growing relationship with the Green Arrow.
Crestfallen that the Black Canary holds no true attraction to him, the Batman, nonetheless, tries to be there for her. Fuming, the Green Arrow confronts the Batman, and the Black Canary. The Batman turns the Batplane over to the Green Arrow, who takes the Black Canary with him to Vietnam, to aid the Flash. Superman, and the Atom, arrive in Iran, as the populace is evacuating, due to a series of powerful earthquakes. While Superman aids in the evacuation, the Atom quells looters. Unbeknownst to the two heroes, a medallion worn by a civilian, Omar Ibn Ali, is really an ancient Mu artifact. The collective consciousness of Mu is channeling their power through the amulet, to create the earthquakes.
When Ali shatters the amulet, of his own accord, to appease another man, the earthquakes stop. Torrential rains create dangerous flash floods in Vietnam. The Flash works to near exhaustion trying to rescue as many people as he can. Unbeknownst to the Flash, a Vietnamese woman, Lok Lu, is praying to another ancient Mu artifact. One that is channeling the collective consciousness of Mu to create the monsoon. The Green Arrow, and the Black Canary, arrive to render aid to the Flash. The Green Arrow pinpoints where the monsoon seems the most intense. The Green Arrow launches a flare arrow to provide illumination against the darkened skies. Having lost all faith in her Gods, Lu destroys the prayer stone, ending the monsoon.
Fortunately for the citizens of Mu, the final talisman they focus their will upon is at the bottom of the sea. Tidal waves begin to form off the coast of California. The Batman spies the starship carrying the survivors of Mu. The Batman leaps to the attack, only to be cut down. The citizens of Mu abduct a surfer, Pete Conk. The citizens of Mu demand that Conk validate humanity's right to life over their own. Conk calls the citizens of Mu out on their fallacies and flaws, then flees. During his escape, Conk throws a wrench into the delicate systems of the Mu starship, causing it to crash into the sea, then explode. The civilization of Mu has truly come to an end. Reassembling, the Justice League of America is at a loss to explain the resolution of the crisis, knowing only that it did not come at their hands.