Julie Blair (Anne Kimbell) is an American artist vacationing at a seaside village in Mexico.

She meets Steve Dunning (Stuart Wade), a marine biologist doing research in the area, and they fall for one another.

She further investigates the stories of a sea monster killing people along with unexplained disappearances in the area.

The mysterious death of a diver inspires Julie to investigate, but Dunning remains very skeptical.

Confronted with the evidence, and now admitting the creature does in fact exist, Dunning uses the submarine to attack the monster.

[6] Ordung later claimed that he hocked his life insurance and sold his apartment to raise $15,000 to pay for the film.

[11] In an interview with Starlog, it was noted that the experience of making this movie hooked Corman on filmmaking as a career.

It also established a professional relationship between Corman, James Nicholson and Samuel Arkoff, that would lead to the creation of American International Productions.

[13] Although Herbert Yates of Republic Pictures had an interest in the film, Corman says the only person willing to put up an advance against income was Robert Lippert.

It did note that the speech on undersea farming was interesting and that Corman's famed penny pinching was on display in the movie.