Under the Jaguar Sun is the story of a couple attempting to save their marriage. They travel to Mexico to try and find the excitement that they have lost in their marriage. They do not have an intimate relationship. The couple travels the country enjoying the cuisine and their time together. They learn about cooking and the ancient culture of Mexico. They enjoy meals and travel to ancient sites. The couple makes a friend in Mexico, Salustiano Velazco, who tells them what they need to experience in Mexico. He loves his country and wants Olivia and her husband to enjoy its land and culture as much as he does.
The couple enjoys the cuisine. The taste of each meal fascinates them and they want to know what spices and food goes into every meal. Salustiano gives them the knowledge they need to appreciate the Mexican cuisine. The Narrator hopes that the sensation of the cuisine that heightens their taste sensations will lead to intimacy with his wife.
They also appreciate the culture. At Tepotzotlan, they explore the church of the Jesuits and their opulence. It gives the feeling that they are attempting to equal the Aztec splendor. They travel to the excavations of Monte Alban where there were human sacrifices to the gods. Olivia becomes obsessed with if the ancient priests ate the human sacrifices. Their guide tells them that vultures carried the sacrifices to the Heavens for the gods. Olivia believes that the priests practices cannibalism and will not let this thought go.
The couple meets up with Salustiano Velazco and tells them about their trip to Monte Alban. Olivia questions him if the priest partook of the human sacrifices. He admits that they could have. They would have had a ceremony so that the sacrificial body would be respected. Olivia questions the spices that they would use to make the human flesh palatable. Salustiano Velazco becomes uncomfortable with the conversation.
During their dinner that evening, Olivia tells her husband that he is insipid. He sees this is being bland and not like the bold Mexican cuisine. He tells her that he has flavors that are subtle and she just has to know how to perceive them. The thought of cannibalism makes their meal more sensual. The Narrator watches his wife eat and fantasies that she is eating his flesh. This idea excites him. Her words show him that for her to enjoy him, he must eat ravenously on her flesh. That night they find the passion that they had lost and have sex. Through the cuisine, taste and thoughts of cannibalism the couple find the passion in their marriage.
