四个大学生为了给自己的生物课挣点附加分,前往福罗里达州的沼泽地进行考察。本来他们是要去研究鳗鱼的,没想到他们的教授也在那里制造了一个基因变种的巨型鳗鱼。同时索伦教授的老友戴尔玛,也在追寻巨鳗的下落。而一个警察则在追踪两个逃跑的罪犯时来到此地。一伙人就这样与巨鳗相遇了……Two prisoners escape through the swamp land in Everglades and the search party is attacked by a giant mutant eel and is considered missing. The Animal Control agent Delmar Coates is searching a missing dog with his ex-wife Sheriff Ruth Gainey-Coates and he discovers the remains of the animal. Meanwhile members of a canoe club organize an expedition through the swamp. When Sheriff Ruth organizes a manhunt to capture the criminals, Delmar informs that his former friend, Dr. Soren Abramson, who is chasing the eel with a group of college students, is the responsible for mutant species. Sheriff Ruth organizes two teams to hunt the prisoners and the eel.