Santo vs. the Mafia of Vice aka Santo contra la mafia del vicio aka Mission Sabotage begins with a pre-credits sequence shot in Acapulco that has Jimmy Santy (Santiago Rogelio Farfán Holguín) singing a catchy tune to three dancing bikini clad ladies. Santo is sat watching them!
Back in Mexico City, the police commandante chews out his detectives for their failure to solve a rash of sabotage aimed at Mexican chemical plants. He sends Raúl to Acapulco to cut short Santo’s vacation.
Meanwhile, mob lawyer Fidel receives a telegram: Mabel Moon is arriving in Mexico to visit her friend, dancer Patricia Ferrer. Fidel orders his henchman Sergio to kidnap Mabel. Fidel’s girlfriend Elsa is curious but he keeps her in the dark.
Sergio tries to pick up Mabel at the nightclub where Patricia works, but she rebuffs him. As a result, Sergio and his thugs break into Patricia’s apartment that night and abduct Mabel. Patricia goes to the police and meets Santo. They learn that Mabel’s uncle is the rich owner of a chemical factory in the U.S.
Mabel is being held captive in Fidel’s house, although she’s allowed to lounge around the pool in a bikini. He tells her that her uncle will pay a large ransom for her safety. Meanwhile, Fidel offers to introduce Elsa to El Santo. Elsa: “The wrestling champion and Secret Service agent” They watch his match that night. Afterwards, Santo is attacked in his dressing room by Sergio and his men, posing as reporters and photographers.
Santo is taken back to Fidel’s house and tossed into a cell in the basement. One of Sergio’s men will impersonate the silver-masked man. However, Santo manages to switch places with his double, who is shot by Sergio and tossed into a furnace! Santo plays along, pretending he is a member of the gang.
Dr. Moon, Mabel’s uncle, arrives. Unknown to her, he is in league with Fidel. For some reason, they decide that Patricia has to be killed. As several henchmen are planting a bomb in her dressing room, a black-hooded man enters and fights them. Patricia, who is having a conversation with Raúl–who has been assigned by Santo to guard her–is not in the room when the bomb explodes. Patricia and Raúl go back to her apartment–which she has modestly decorated with a giant blowup of her own face that takes up most of one entire wall–and spend the night together.
Later, Raúl drops Patricia off at his mother’s house, to keep her safe. His mother says her husband, also a policeman, was killed on the job: “A medal and a grave, that’s all he got for dedicating his life to fighting crime.” She warns Patricia not to fall in love with Raúl.
Fidel and Dr. Moon want to recover a shipment of drugs that has been seized by the Mexican police, and this is why they have created a “fake” Santo. Meanwhile, Santo sneaks into Elsa’s bedroom while she’s out, and discovers her Interpol credentials. Later, after he’s saved her from Sergio’s lecherous advances, Elsa asks for her credentials back, and they clinch.
Sergio, Santo and the gang attack the police with gas bombs and steal back the drugs, before the police can burn them. The commandante suspects that Santo is crooked, but Raúl points out that the gas had been adulterated so it wasn’t deadly, probably Santo’s work. Santo contact Raúl by radio, informing him that Dr. Moon is the head of the organization, and that the drugs are going to be smuggled out of Mexico that night.
Santo, Elsa, and Mabel are trapped in the warehouse that contains the drugs; Fidel, Dr. Moon, Sergio and the rest of the gang try to kill them, but Raúl arrives to lend a hand, followed by more police. Dr. Moon is shot and killed; Elsa shoots Fidel, and the rest of the gang is captured or killed.
Elsa and Santo are enjoying some time off in Acapulco, when she receives orders to depart for Hong Kong. Their careers will always keep them apart. Santo seems a little depressed, until two buxom blondes in bikinis arrive to keep him company. The film ends with Santo and the blondes zipping around in a speedboat (as you do!).