While lying on an operating table, wounded American Mike Cormack describes for Capt. Peña of the Puerto Rosario police the dramatic events of the previous week: At a Las Vegas casino, Mike, a special security officer, is approached by a mysterious, wheelchair-bound man named Barzland, who offers him $5,000 to retrieve a ruby he claims is owed to him. Aware that Mike, a former prosecutor, was once engaged to a beautiful woman named Janet and had a breakdown after she married dashing pilot Eduardo Martin, Barzland explains that he hired Eduardo and his aviation partner, Fernandez, to transport the ruby from Puerto Rosario. The plane crashed, with Fernandez at the controls, and the ruby turned up missing. Although suspicious of Barzland, Mike agrees to go to Puerto Rosario and renew his acquaintance with Janet in order to find out what happened to the ruby. Upon arriving in the tiny Caribbean nation, Mike strolls through the marketplace near his hotel and runs into Janet. Pretending not to know him, Janet leaves the market abruptly with her servant, Miguel. Later, however, Janet summons Mike to her home and tells him that Eduardo is serving a life sentence for Fernandez’ murder, as the police had determined that their plane had been tampered with before Fernandez took off. Janet also admits that Eduardo and Fernandez’ business was failing and they were on the verge of selling the plane when they were offered the ruby job. After insisting that Eduardo did not kill Fernandez, the seductive Janet hugs Mike, expressing her fear and loneliness. The next day, Mike goes to the airport and learns that a mechanic named Carlos had worked on Eduardo and Fernandez’ plane. Mike looks for Carlos at his home in the country and learns from a young boy and Carlos’ mother, who is busy making pottery, that Carlos is at a nearby cockfight with his champion rooster. At the cockfight ring, Mike offers Carlos money for information about the ruby, and Carlos, excited, promises to speak with him after the fight. As the match is about to begin, however, the lights go out and Carlos is murdered. Everyone present is questioned by the police, and while being interrogated by Peña, Mike repeats Janet’s assertion that Eduardo was wrongly convicted. Peña scoffs, revealing that Eduardo confessed after evidence tied him to the sabotaged plane. Now unsure, Mike goes to see antique dealer Paul Armand, Janet’s friend and advisor, and asks him about the ruby and Fernandez’ murder. Paul also insists that Eduardo is innocent and claims no knowledge of the ruby. Later, in Mike’s hotel room, Janet states that, while she no longer loves Eduardo, she cannot abandon him and asks Mike to help him escape. Mike balks until Janet reveals that she was the one who tampered with the plane’s fuel switch and Eduardo confessed to protect her. Fearing that Janet will implicate herself to Peña, Mike agrees to help, then asks Janet about the ruby. When Janet responds with hysterics, Mike kisses her and drops the subject. Leaving Janet sleeping in his room, Mike sneaks back to her house and discovers the place ransacked and Miguel fatally wounded. Mike then is attacked from behind and wakes up to find Barzland and his assistant, Lawrence, standing over him. After Barzland’s thug, Torbig, beats Mike for information about the ruby, Mike is locked up but escapes and throws Torbig in an alligator-infested pond. Mike hitches a ride back to town and arranges to meet Janet at Paul’s antique shop. There, Mike angrily confronts Janet about the ruby, and she finally admits that Fernandez hid the gem before the crash, and she, Paul and Eduardo intend to find it. After Janet promises to share the ruby’s worth with him, Mike agrees to accompany her and Paul to the island where Eduardo’s prison is located and undertake the escape plan. Near the island, Mike leaves Janet and Paul in their charter boat and, under cover of darkness, rows to the island. As soon as Mike is out of sight, Janet orders Paul to sail back to Puerto Rosario, and when he balks, shoots him. Mike, meanwhile, sneaks past the prison’s guards and locates Eduardo’s cell, but Eduardo laughingly tells him that he has no intention of escaping, as he is sure that Janet has tipped off the police, hoping he will be shot. Eduardo then tells the stunned Mike that Janet sabotaged the plane thinking that he would be flying that day, because she wanted to collect on his $100,000 life insurance policy. Later, after conferring with Peña, Mike surprises Janet at her house and claims that Eduardo was killed during the escape and that he knows about the $100,000. Mike kisses Janet and, convincing her of his devotion, gets her to admit that she conspired with Paul to murder Eduardo and Fernandez and had Miguel kill Carlos in order to steal the ruby and collect the insurance money. Enraged by her nonchalant confession, Mike grabs Janet, who struggles and knocks over a small ceramic statue made by Carlos’ mother. Among the shattered pieces, Mike sees the giant ruby, a relic stolen from a local museum. Peña suddenly appears, having heard Janet’s entire confession, but before he can arrest her, Barzland and Lawrence take him by surprise, and a shootout ensues. Mike is shot and wounded after felling Lawrence, then wrestles with Barzland until Barzland falls out the window to his death. In the operating room, Mike concludes his story and later watches Janet being led away by police. Sadder but wiser, Mike bids Peña goodbye and heads for the airport.