After being jailed for solving another mystery, the Mystery Inc. gang stumbles upon another mystery: a gruesome monster lurking underneath the town and cocooning everyone who comes near in green goop.
Brainiac, once Krypton's all-knowing planetary computer, comes to Earth as part of his information-gathering trek across the galaxy. But, as Superman discovers, Brainiac's intent after gathering the world's knowledge is to destroy the Earth.
Rogue and Wolverine duck a squad of soldiers when the nationwide alert goes out against mutants, while Storm and Beast go into a meeting of Congress to defend themselves. Meanwhile Juggernaut goes on a rampage and the X-Men feel obliged to take him down.
After toxic chemicals transform janitor Rudy Jones into the energy-draining Parasite, he imprisons Superman, intent on keeping the Man of Steel as his own personal power source.
Bruno Mannheim's Intergang terrorizes Metropolis with hi-tech weapons from Darkseid, while SCU Inspector Dan Turpin goes on a personal hunt for answers.
Radio shock-jock Leslie Willis is turned into a being of pure electricity, and begins her media-crazed rampage to drain Metropolis' power and kill Superman in the bargain.
"Meltdown" is the best rated episode directed by Curt Geda. It scored 8.7/10 based on 9 votes. It was written by N/A. It aired on 2/13/1999 and is rated 0.1 points higher than their second-best episode, "Shriek".