Whilethehotroddersandmotorcyclistsarehavingarock-and-rollbeachparty,abarrelofradioactivematerialisunloadedfromapassingship,plungestothebottomandsplitsagainstajaggedrock.Ablackliquidoozesoutandcoversashapelessmassontheoceanfloor,whichsuddenlymovesandbecomesanencrustedviciousmonster.Soonthereareseveralmonstersandtheymusthavehumanbloodtosurvive.Tinaisthefirstvictim,andfootballheroHankGreenandairheadElaineGavinenlisttheaidofherscience-professorfather,Dr.Gavin,tosolveandcapturethekiller.Notworkingfastenoughtopreventtheattackontwentyteen-agersataslumberpartynorthekillingofthreegirlmotorists,Dr.Gavinfindsanarmlostbyoneofthemonstersanddiscoversthatonlysodiumwilldestroythemonsterswhosecompositionismostlywater.CantheygatherenoughsaltinsouthernCaliforniatoputanendtothishorror?