A baby alligator that was brought home by a young girl from a vacation in Florida is flushed into the sewers by her dad. 12 years later an evil pharmaceutical corporation has been experimenting on animals with a growth serum and they’ve dumped the test subjects into the sewers. The alligator has fed on the carcasses and is now a giant ravenous 36 foot long alligator and is roaming the sewers looking for food.
Soon body parts of sewer workers start showing up. World weary police detective Robert Forster, who has Dirty Harry’s habit of getting his partners killed, is assigned to the case. While checking the sewers Forster and a young cop run into the big gator and the cop gets eaten. Nobody believes Forster’s story until a reporter takes some pictures while getting killed. Forster then teams up with a reptile expert (Robin Riker), who was the little girl who brought the alligator to the city.
The cops starting closing in and the alligator busts out the sewers and runs amok in the city killing and maiming tons of people. In the middle of the media circus the city brings in a big animal hunter (Henry Silva) to kill the beast. Before you know it more people are dead and a wedding is ruined.
Made to cash in on the Jaws craze, John Sayles wrote the screenplay for the movie and used the money he made from this and a couple other movies he wrote for Roger Corman (Piranha, Battle Beyond the Stars) to finance his own independent movie Return of the Secaucus 7. The film is entertaining for a low budget giant monster alligator movie and it actually manages to create some suspense.