The creature, Sludge, climbs out of the sewers in Manhattan right in the middle of some gang members performing a drive-by.

He crushes their car and so they decide to try and kill him. After being shot and stabbed Sludge learns of his healing abilities. Also for rapid cell growth when coming into contact with human skin.

We learn of Sludge's origin, a crooked cop by the name Frank Hoag, who refused to kill another officer of the law. He was pursued through the building and shot up in the lab, and dumped, where the chemicals mixed with his body, giving birth the Sludge.