Half-man, half crab, it lives in a cave near Piedras Blancas and only comes out of its cave to eat the offerings of the enigmatic lighthouse-keeper Sturges, whom everyone else considers crazy and superstitious. But as this campy horror movie shows, the lighthouse keeper isn't crazy at all; he just exercised poor judgment, for thanks to him, the lobster man develops a taste for human blood and embarks upon a killing spree by ripping the heads off two fishermen. The locals investigate and this creates even more problems as the killer crustacean makes his way towards the favorite teen hangout "Love Beach." The monster bears a suspicious resemblance to the "Creature of the Black Lagoon."