“THE LURKER BELOW.” Prof is dying of an all-consuming fungus infection. Rocky, June, Ace and Red rush him to their jet. Gaylord Clayburne, playboy/Challenger wannabe, learns Prof is sick and finds a specialist to heal him. Ignoring Clayburne, the Challengers zoom off to Perdition, Pennsylvania, a farm town, but as soon as they land, the Challengers are mobbed by farmers with pitchforks. Dr. Monroe calls off the farmers and relates the town’s history to the Challengers. Seventy years ago, a man summoned a demon to the town. Enthralled, the locals sacrificed strangers to the “god” until Swamp Thing came to town and collapsed its cave, burying the monster “forever.” Behind the scenes, we see the fungus lived on and still infects many locals.
Prof. Haley is dying of a strange infection, and according to the Challenger's computer, the only doctor who can save him is in Perdition, Pennsylvania. But upon arrival in Perdition, the Challengers are met with hostility by the locals.