The film earned over $86,572,238 worldwide in box-office receipts. It also helped launch Turner to stardom, reintroduced Douglas to the public as a capable leading man, and gave Zemeckis his first box-office success. Decades later, it retains critical acclaim, with a 86% approval rating on Rotten Tomatoes.
Joan Wilder (Kathleen Turner) is a lonely romance novelist in New York City who receives a treasure map mailed to her by her recently-murdered brother-in-law. Her widowed sister, Elaine (Mary Ellen Trainor), calls Joan and begs her to come to Cartagena, Colombia, because Elaine has been kidnapped by bumbling antiquities smugglers Ira (Zack Norman) and Ralph (Danny DeVito), and the map is to be the ransom.
Hastily flying to Colombia, Joan is detoured from the rendezvous with Ralph by Colonel Zolo (Manuel Ojeda), the man who killed Elaine's husband. Joan ends up in the jungle and is almost killed by Zolo, but is saved by the swashbuckling American bird exporter Jack T. Colton (Michael Douglas). For getting her out of the jungle and to a telephone, Joan promises to pay Jack $375.
Jack and Joan elude Zolo, who wants the treasure for himself and who chases them with military police, which he commands as a "private army". After spending a night hiding in a crashed marijuana smuggler's C-47 airplane, they encounter a drug lord named Juan (Alfonso Arau), who is a big fan of Joan's novels and who helps them escape from Zolo.
After a night of dancing and passion, Jack suggests to Joan that they find the treasure before handing over the map. They follow the clues and find the treasure: an enormous emerald called El Corazon ("The Heart"). Unknown to Jack and Joan, their trail has been picked up by Ralph, who tries to take the emerald and taunts Joan that Jack would have done the same.
But Ralph flees without the treasure when Zolo appears, and Jack and Joan are chased into a river and go over a waterfall. Jack and Joan end up on opposite sides of the raging river; Joan has the map, but Jack has the emerald. Jack directs Joan to Cartagena, promising that he will meet her there with the emerald, but she is skeptical, owing to Ralph's taunts.
In Cartagena, Joan contacts Ira, but cannot find Jack. She meets with Ira and Ralph at their base (an old fortress) and makes the exchange. As Joan and Elaine attempt to leave, they are stopped by Zolo and his men, who have captured Jack. Zolo demands the emerald and threatens Joan with the crocodiles that Ira keeps as pets. To save Joan, Jack surrenders the hidden emerald to Zolo, but a crocodile bites off Zolo's hand and swallows it along with the emerald.
As a furious gun battle takes place between Zolo's soldiers and Ira's gang, Joan and Elaine dash for safety, but they are pursued by the enraged Zolo, who eventually catches up to them, attacking Joan with the knife that she initially tossed at him. They engage in a desperate and fierce struggle with the knife. Jack tries to stop the crocodile from escaping but lets it go when he sees that Joan is in grave danger. After out-fighting and out-witting Zolo during the protracted death struggle, Zolo gets up, entirely furious, and charges Joan, who eventually dodges his wild knife slashes, knocking Zolo into the crocodile pit. Ira and his men escape, but Ralph is left behind as the authorities arrive. After a kiss, Jack dives into the water after the crocodile, leaving Joan behind with her sister.
Some time later, Joan is back in New York City, delivering a new manuscript based on her adventure, and her publisher, Gloria (Holland Taylor), loves it. Returning home, she finds Jack waiting for her in a sailboat. He caught the crocodile (which he says died from a "fatal case of indigestion") and had it made into a pair of boots, sold the emerald, and bought the boat he had told Joan was his dream. They go off together, planning to sail around the world.