The Justice Society of America are trapped within an ectoplasmic bubble created by Dr Fate - in order to sve themselves and Earth -2 from the menace of Aquarius! Aquarius has overcome Starman and stolen his cosmic rod - and this piece of equipment added to his own power have made him a threat to the entire universe! Aquarius has already sent Earth -2 to another dimensional plane, and should the Justice Society perish, then Earth -2 will die along with them!
Now, thanks to the Red Tornado, the Justice League are about to arrive on the scene in "Where Death Fears to Tread!" Crossing the interspatial divide between dimensions, the JLA are on their way to try and rescue the Justice Society. As they travel, Green Lantern's attention is drawn to the anti-matter universe, which they pass close to and which itself may one day pose a threat to the universe.
The League arrive just in time to stop Aquarius using all his remaining energy to destroy the JSA. Surprised at the arrival of other beings and not yet up to full strength, Aquarius flees, but not before he leaves the Justice Society members with a mental command.
As the Justice League rush to greet thier friends, each one in turn is attacked by their JSA counterpart, who is now under the command of Aquarius. A monumental battle begins with the two Supermen going hammer and tongs at one another. Batman manages to overcome Dr Mid-Nite thanks to his infra-red lenses, while the Atom and the Flash team up to overcome Dr. Fate. Since Alan Scott's power ring ran out of juice days ago, it is a simole matter for Hal (Green Lantern) Jordan to capture his counterpart and then to concentrate his will power on finding Aquarius and have the stellar being return to the fray. Meanwhile, Black Canary finds herself glued to the floor by Green Arrows "gum" arrow, but the emerald archer is then jumped from behind by Larry Lance - husband of the Black Canary, who has been in on this case from the beginning.
While all of this infighting is going on, Green Lantern's power beam has reached Aquarius. Aquarius fights back using Starman's cosmic rod, and builds as cosmic ball of power which he intends to fire back at Green Lantern. However, the space being has not mastered the use of the Cosmic Rod and the ball of power heads for the first person it can sense - the helpless Black Canary! Seeing his wife in trouble, the bold Larry Lance dives in front of her and takes the full impact of Aquarius' cosmic power ball - thus sacrificing his life for the sake of his wife.
The sphere of power bursts and suddenly, all around them, the Justice Society sees their world return to normal - all apart from Black Canary - whose world will never be the same again. Alan Scott goes on a guilt trip, but Hal Jordan talks him round and the 2 GL's share Scott's oath as he recharges his ring. Superman of Earth-2 leads a ceremonial tribute to Larry Lance, but Aquarius appears on the scene. The space being taunts the superheroes, and as Wonder Woman comforts the grieving Black Canary, the rest of the JLA and JSA pursue Aquarius into deep space.
The heroes recognise that Aquarius is now heading for Earth-1 and that he could destroy the very fabric of the universe. As Aquarius enters the cosmic gateway between the 2 earths, he leaves behind a space warp which traps the heoroes. However, the two Green Lanterns burst through and decide to go it alone against Aquarius. Passing the Anti matter universe the two heroes goad Aquarius. Using their power rings to create negative energy around themselves, they trick Aquarius into following them into the Negative universe, and as his positive matter touches the negative matter, Aquarius perishes in a huge explosion.
Back on Earth-2, the heroes say their fare-wells, but Black Canary decides she can't stay on Earth-2 as it would be full of painful memories for her, and Superman welcomes her to Earth-1.