The Bat Woman (1968)

Gloria (a.k.a., the Batwoman) is a wealthy, crime-solving, female wrestler. She is called to investigate a series of murdered wrestlers that are found floating in the ocean offshore from Acapulco. While the victims appear to have drowned, in each case, the contents of the victim's pineal gland have been removed. Working with FBI agent Mario Robles, Gloria follows a trail of clues to the eccentric neurosurgeon, Dr. Eric Williams. Based on-board his floating laboratory, the Reptilicus, Williams is striving to create a gilled human by injecting small fish with the glandular extract. Subsequent exposure to radiation grows the resulting mutant to the donor's size. He dreams of creating an army of Gill Men to take control of the world's oceans. HIs experiments require one too many victims. He always uses wrestlers as donors because he wants his mutant full of vigor. Gloria and Mario start staking out the local wrestling gym, hoping to see the next victim being set up. It is easy for Gloria to blend in as she is a proficient wrestler herself. Once Williams has been identified as the perpetrator, the Batwoman steals aboard his boat. She is nearly apprehended. Now that Williams is aware of her being on his case, he uses his minions to try to capture her. When that fails, he attaches an electronic device to her cape that will make her the target of his first Gill Man's hunt.