The Beach Girls and the Monster

Three surfers and their girlfriends arrive at the beach, where Bunny runs away from her boyfriend in a playful manner. Later, Bunny is found dead near a cave, having been attacked by a seaweed-covered humanoid creature. This sets a mysterious and dangerous tone for the story, hinting at a deadly threat lurking in the scenic location.

The sheriff finds strange footprints left in the sand at the crime scene and takes a cast for further analysis. These footprints are unusual and suggest the presence of a creature not belonging to any known terrestrial animal, adding an element of mystery to the murder. The footprints lead to ongoing investigations about the creature's origins.

The sheriff consults oceanographer Dr. Otto Lindsay, who believes the footprints might belong to a 'fantigua fish'—a large, carnivorous, man-eating fish that could exist in an anthropomorphic form due to mutation. This scientific insight introduces a potential explanation for the creature, blending science fiction with horror.

The story introduces Dr. Lindsay's household, including his son Richard, his wife Vicky, who is flirtatious and drinking heavily, and Richard's friend Mark, a sculptor with a limp from a car accident caused by Richard. Tensions and personal dynamics hint at underlying conflicts within the household and set the stage for later events.

Richard and his girlfriend Jane decide to avoid the beach and instead swim in the pool. Meanwhile, Vicky goes to the beach alone and unknowingly nearly falls prey to the creature, highlighting the ongoing danger and foreshadowing future attacks.

Vicky returns home from the beach and models for Mark, flaunting her flirtatious nature. Her relaxed attitude contrasts with the lurking threat of the creature, and her behavior suggests she may unknowingly attract danger.

Dr. Lindsay tries to persuade his son Richard to rejoin his research, but Richard prefers attending a nighttime beach party. Meanwhile, Vicky reveals she plans to leave her husband, overhearing him making a date, which adds tension and personal conflicts within the household.

At the beach party, the creature attacks and kills a surfer named Tom, slashing his face. Mark witnesses the attack but cannot intervene in time. During the chaos, a strange rubber strip is found in the sand, hinting at the creature's presence and possible origins.

A heavily intoxicated Vicky returns home and receives a note asking her to speak in Mark's room. There, she is attacked and scarred by the creature. Mark finds a rubber mask in the kitchen and fights the creature, eventually stabbing it, revealing Dr. Otto Lindsay in disguise.

Mark dies from his injuries after tearing off the creature's mask, revealing Dr. Lindsay as the monster. Richard and Jane find Mark dying and alert the police. They join a car chase driven by the sheriff to catch Dr. Lindsay, who is attempting to escape.

During the pursuit, Dr. Lindsay loses control of the car, which crashes and catches fire, killing him. The sheriff suspects Lindsay's actions were motivated by a desire to protect Richard, but his motives remain ambiguous amid the chaos.