Something ancient lurks in the surf off Sea Bright Beach. It swims silently, can breathe air and walks upright. It's also very, very hungry and not for seafood anymore. Tonya, Rodney and Rupert are out-of-towners joining a crowd of young people gathered on the beach for an all-weekend music marathon. Even after several townspeople are torn apart and devoured by the humanoid creatures, the partygoers remain oblivious to the horror that has risen up from the sea. They dismiss local girl Tess as a weirdo and refuse to heed her cries and warnings that monsters roam the beach, hunting for human flesh and that hundreds of buried egg sacks are ready to hatch at any moment.