The agent from the Environmental Protection Agency Frank and his partner Tillman are researching the water of Lake Placid when a huge crocodile attacks and shatters Tillman. Only parts of one arm and one leg are retrieved. Frank tells Sheriff Riley what happened to Tillman and in principle he does not believe. Only when Riley sees Tillman's remains, he goes to investigate with Frank and the Fish and Willd Life agent Emily, who is his ex-wife. Meanwhile, Riley's son, Scott, who is spending a couple of days with his father, befriends the local Kerri and she invites him to go with her boyfriend and a couple of friends to bath in the lake. Other tourists are camping at Lake Placid. Out of the blue, Riley and his mates find Tillman's head and are attacked by the crocodile that shatters their boat. Sheriff Riley asks his deputies to close the lake and Deputy Dale Davis to bring weapons and another boat to the group. The wealthy hunter Struthers and his partner Ahmad arrive in a hydroplane informed by a snoopy local reporter. Meanwhile, the crocodile is attacking people that are at the lake and soon Sheriff Riley learns that there is more than one crocodile in the lake and the female is protecting her nest.
