This is an edited version of a ten-year-old film, _Sea Fiend, The (1936)_.

A schooner disappears at sea without a trace. Years later, evidence of possible survivors prompts the mother of the schooner's mate Jose to hire a tuna boat to investigate. They discover the lad living happily on a South Seas island, and, when he refuses to leave with them, they abduct him. However, Jose gets revenge by leading the ship into the lair of a mysterious giant manta ray.—Jeremy Lunt <[email protected]>

On June 29, 1945, E. M. Landres and Louis Weiss paid Russ Vincent and George Moscow the princely sum of $500 for the exclusive world-wide rights to an eight-reel feature called "The Great Manta," and also tossed in the rights to an eight-reel negative and sound-track (Spanish language version of "The Sea Fiend")of "Diablo Del Mar." Several years earlier, Vincent and Moscow, had acquired the rights to the 1936 film "The Sea Fiend" and had renamed it "The Great Manta." So, Weiss Brothers took three films---"The Sea Fiend," "The Great Manta" and "Diablo Del Mar"---tossed in some footage from 1930's "Hell Harbor" and a lot of stock footage from geography-exploitation films...and delivered "Devil Monster." Story remains the same in which a young seaman, Robert Jackson, in love with a San Pietro schoolteacher, Louise, goes to the south seas in search of her long-missing fiancée, Jose Francisco. Once found, Jose opines he had rather not have been found, and this leads to mucho trouble...in several languages—Les Adams <[email protected]>