Reports of a lizard-man terrorizing the Everglades bring Spiderman to Florida, where he finds that a Doctor Conner, by testing a swamp fever serum upon himself, has changed into an intelligent lizard. The lizard that Conner has become intends to use a beaker containing the serum, which it confiscates from Conner's laboratory, to convert alligators into reptiles that share its level of intelligence, to follow it in conquest of humanity. Spidey applies his knowledge of science to conceive an antidote to the serum and confronts Conner's lizard alter-ego at an old, Spanish fort, webbing the bipedal reptile before it can release the serum into the Florida swamps, and forcing it to drink the antidote that changes it back to Conner, who does not remember any of his acts as the Lizard but is immensely grateful for Spidey's help, as are his wife and son.