On the eve of the festival commemorating the return of the original Superman from his long exile in the heart of the sun, the mightiest heroes of the year 85,271 - JUSTICE LEGION A - come back in time to invite the greatest heroes of -the 20th century - the JUSTICE LEAGUE OF AMERICA - to travel to the future and take part in the celebration,

But both teams fall victim to a plot millennia in the making. Stranded in the far future, the LA are hunted as dangerous renegades. Meanwhile, their counterparts in the Justice Legion A must find a cure for a deadly virus they have unwittingly brought into their past - our present - and deal with traitor in their midst.