Mermaids of Tiburon

Dr. Samuel Jamison is approached by Ernst Steinhauer with a rare, unusually large flame pearl found in Tiburón's coastal waters. Steinhauer asks Jamison to confirm whether there are more pearls. Jamison weighs the offer and the risks of an expedition, considering the potential scientific payoff against the dangers of treasure hunting.

Jamison travels to meet Steinhauer for the planned expedition but finds Steinhauer missing upon arrival. He reports Steinhauer's disappearance to authorities and decides to proceed with the expedition on his own. He hires a charter boat to lead the search and secure passage to Tiburón.

Unknown to Jamison, Milo Sangster has learned of the treasure and murders Steinhauer to take it for himself. Sangster tails Jamison with the help of an unsuspecting skipper, Pepe Gallardo. During the pursuit, they dump Steinhauer's body overboard to avoid arousing suspicion.

Jamison arrives in Tiburón and begins to investigate the island's environs and its fauna. He dives into the coastal waters, drawn by the mystery of the pearl clams. His exploration sets the stage for a confrontation with the hidden undersea world.

Jamison encounters a group of mermaids and a pet killer shark in the coastal waters. After a cautious display, he signals that he means no harm and the mermaids lead him to an underwater grotto. The grotto is filled with numerous giant clams, the source of the pearls.

Sangster arrives at Tiburón and disregards Pepe's protests as he begins to throw lit dynamite into the water to take Jamison out. The blasts stun Jamison, who struggles to reach the surface and stay afloat. Meanwhile, Sangster and Pepe continue their own search for the pearl-laden clams.

Jamison, recovering on the surface, boards Sangster's trawler and uncovers evidence that Steinhauer has been murdered. The two men return to the boat, catching Jamison off guard and forcing a confrontation. The discovery raises the stakes as Jamison realizes Sangster's murderous intent.

Sangster clubs Jamison and prepares to shoot him; Pepe tries to intervene but Sangster throws him overboard, where he is devoured by the shark. Jamison fights back as Sangster uses a magnesium flare to ward him off. The men struggle amid chaos on the trawler.

During their struggle, the magnesium flare is dropped near Sangster's cache of dynamite, igniting it and destroying the trawler. Jamison is knocked aside but is saved from the flames by the sudden appearance of mermaids. Sangster escapes in a lifeboat as the vessel detonates.

Sangster invades the grotto again and encounters the mermaids. He shoots one of them with his speargun, prompting the mermaids to lure him into a narrow underwater fissure. His oxygen runs out, and he drowns just inches from the surface.

Jamison makes it to safety with the mermaids' help, and the mermaids vanish as he regains his breath and composure. His world view is enlightened by the strange encounter, and he departs with a vow to return one day.

Jamison departs Tiburón, carrying the lessons learned from his encounter with the mermaids. He commits to returning someday to further understand the ocean's mysteries and the beings who inhabit its depths.