Batman is caught in the middle of a vicious confrontation between Poison Ivy and Allergent, a deadly new villain killing Gotham's flora with an insidious defoliant.

Batman and Robin, along with the major crimes unit, investigated an explosion and strange gas in a Gotham City park. The gas turned out to be a defoliant, killing all plants in its path. The police closed in on the man, dubbed the Weedwhacker - a man who suffered from extreme allergies. He escaped their pursuit, but the Batmobile gave chase.