After securing some business at the Cuzco, Peru, airport, tough American tour guide Harry Steele is summoned to a cantina by old acquaintance Ed Morgan. Down-and-out Ed tells Harry about a job involving an escaped Romanian woman, who is on her way to Cuzco from La Paz, then questions him about a stone Incan treasure map, the missing piece of which Ed knows was found recently by a local Indian. Harry claims ignorance of the map, which legend says leads to a solid gold, jewel-encrusted relic in the shape of a sunburst, and leaves, but is soon shot at by a sniper sent by Ed. The sniper misses, however, and Harry storms back to the bar to confront Ed. Ed, who has been seeking his fortune in Peru for thirty years, freely admits he hired the sniper to frighten Harry and criticizes him for lying about the map and excluding him from the treasure hunt. After dismissing Ed’s complaints, Harry leads a group of tourists to the local museum. There, he slips away from the group and fits a piece of broken, inscribed stone into a small replica of Machu Picchu, an Incan temple, which is on display in one of the rooms. Harry quickly studies the replica before returning to the group and noticing an attractive young woman with a suitcase, trying to blend in. Later, at the tourist hotel, Harry meets the woman, Elena Antonescu, who turns out to be the fugitive from Romania. Elena reveals that she was forced out of Bolivia, without papers, and begs Harry for help getting to the United States. Aware that Elena has only fifty dollars to her name, Harry coldly declines until she admits that the Romanian consul, Anton Marcu, who followed her to La Paz, has his own airplane. After telephoning Marcu in La Paz and telling him about Elena’s whereabouts, Harry makes a deal with Elena that he will help her get to Ecuador if she helps him steal Marcu’s plane. The next day, Harry meets Marcu at the airport and takes him to Elena in the hotel bar. Harry plies Marcu with alcohol and then slugs him, assuring he will be unconscious long enough for Elena to steal the keys to his airplane. Before they leave for the airport, Ed demands that Harry take him along, but Harry refuses. Under cover of darkness, Harry and Elena slip by airport security and steal Marcu’s plane, taking off while being shot at by police. Hours later, Harry lands the plane near a river in the Andes Mountains and finally tells Elena their destination—Machu Picchu. Unhappy but trapped, Elena hikes with Harry to the ruins, where an archaeological dig, led by American Dr. Stanley Moorehead, is being conducted. Harry and Elena tell Stanley and Pachacutec, the leader of the local Indian tribe, that Harry is Elena’s pilot and that their plane ran out of gas a few miles away. Although Pachacutec and his sister Kori-Tica are suspicious of Harry and Elena, Stanley is gracious and bandages a small cut that Elena sustained in a fall. As Stanley’s crew works to uncover the tomb of an Incan king, Harry finally tells Elena about the sunburst, revealing his belief that the treasure is in the tomb. After Harry confesses he disabled the crew’s radio and intends to steal the sunburst, Elena expresses her disapproval but admits she is not in a position to stop him. That night, while the Indians perform sacred rituals in anticipation of the tomb’s opening, Stanley and Elena talk under the stars and share a kiss. The next day, Ed appears at the ruins, claiming he came in response to a distress call Harry made before abandoning the plane. Although annoyed by Ed’s presence, Harry goes along with his story. Later, after telling Elena that, if she wanted, she could get the gentlemanly Stanley to marry her, Harry comments that she is more his type than Stanley's and kisses her. At first, Elena responds to Harry’s passion, but when he nonchalantly instructs her to lead Stanley on until they are ready to leave, she storms off, disgusted. The night before the tomb’s unearthing, Stanley proposes to Elena, but she is noncommittal. While Harry and Ed hang back, Stanley leads the way into the tomb, where a carved stone version of the sunburst is found. After Stanley tells Pachacutec that the gold sunburst does not exist, Pachacutec sadly informs his people that the legend, which says that the Incas will be resurrected with the finding of the gold sunburst, is false. Harry declares he is leaving the next day and asks Elena to join him, but just before dawn, he sneaks back to the tomb and, guided by the map piece, discovers the gold sunburst hidden in a wall. Unknown to Harry, Ed has followed him into the tomb and, at gunpoint, demands the sunburst. Before Harry can react, Pachacutec bursts in. Ed shoots at him, then snatches the sunburst from Harry and runs from the ruins, firing wildly at the pursuing Indians. Harry, however, catches up to Ed on a cliff and fights the exhausted older man for the sunburst. Harry grabs the sunburst just as Ed stumbles and falls to his death. For a moment, Harry revels in his victory, then walks back to the ruins and presents Pachacutec with the sunburst. Admitting that finding the sunburst was more important to him than owning it, Harry proposes to Elena, who happily accepts.