Penniless but full of ideas, Steve Martin and Johnny Gambi, engineers who served in the Navy during World War II, walk down a quiet road on the gulf coast of Louisiana. Teche Bossier, owner of the Port Felicity Fish Co., agrees to drive them into the shrimping town of Port Felicity in exchange for five dollars. Upon reaching their destination, Gambi rents a shrimp boat from Dominique Rigaud, although the fisherman's daughter Stella distrusts the strangers immediately. Gambi and Steve use the boat to show potential investor Kermit MacDonough the location in which they plan to drill for offshore oil. Claiming that he has designed a drilling platform that can withstand any storm, Steve estimates that by investing one million dollars now, they will soon tap an oil reserve worth two billion. His enthusiasm is so infectious that MacDonough agrees to fund the project against the advice of his secretary, Rawlins. MacDonough warns Steve, however, that he must discover oil within three months, or his company, due to huge investments made in an offshore oil lease, will put them both out of work. Several weeks later, Gambi meets and falls for Stella's younger sister Francesca, but, according to custom, she has been betrothed since childhood to Philippe Bayard. After singing a love song in the Bon Chance, a local gathering place, Philippe is distressed to see Francesca enter with Gambi. Teche, who good-naturedly calls the oilmen "foreigners," agrees to help Steve and Gambi, but Stella, claiming that she learned about "their kind" during her stay in Chicago, refuses to accept Steve's statement that oil will be good for the town. Nevertheless, the outsiders hire a crew and begin their search for oil. When Teche sees them drop dynamite charges into the gulf, he begs them to stop, believing that the explosions will kill the shrimp and worsen an already dismal shrimping season. Steve maintains that the charges are safe, but Teche returns to town and incites the fishermen to form an angry mob. Steve finally scares them away by exploding sticks of dynamite behind them, and he placates Stella by warning Gambi to stay away from Francesca. "Go back to your people," Steve gently advises Francesca. With one month gone, Steve drives the building crew relentlessly, and the platform and rig are completed on schedule. Steve immediately orders the drilling crew to get started, and the exhausted Gambi is relieved when a hurricane warning gives the men an excuse to take the night off. Gambi and his men enter the Bon Chance with Francesca, and Philippe, furious, punches his rival and starts a brawl. The sheriff arrests the oilmen, and Francesca angrily denounces all the men. Determined to have Gambi fired, Stella visits Steve at the rig, where he explains that if he could pull up a resource that has been in the earth for millions of years, then he will truly have accomplished something. Stella finally abandons her suspicion and kisses Steve, but back in town, Philippe persuades Teche to help him destroy the oil rig. With the hurricane winds rising, Philippe climbs onto the platform and lights a bundle of dynamite, but Steve sees him and the two men fight. Philippe trips and disappears under the waves, and Steve, horrified, assumes that Stella was involved in Philippe's plot. The rig survives the storm, and in the morning, drilling begins. Eight days before the deadline, however, MacDonough visits Steve and sadly delivers the news: The board of his company, fearing a penalty for non-payment on their lease, has voted to stop the drilling operation on the following day. MacDonough has already spent all of his own money, and the crew is unable to work for no pay. At that moment, Gambi returns from town, announcing that he has just married Francesca. Steve punches Gambi, who loudly chastises Steve for having driven him and the men too hard. Steve tells them all to leave, intending to do the drilling himself, whereupon Gambi hesitates and then persuades the crew to remain. While the men are drilling, they discover that the troublesome shrimp that have been clogging the valves are actually the huge golden shrimp that have so long eluded the local fishermen. Later Steve takes Francesca to the rig, infuriating Dominique, who inflames the fisherman by declaring that the oilmen will steal their daughters and destroy the town. At Stella's request, Teche warns Steve that every boat in town is on its way to the rig. Feigning ignorance about the golden shrimp, Steve asks Teche if he can help him get rid of the creatures and then addresses the furious mob. Francesca's marriage is a happy one, he assures the men, and moreover, oil will bring progress to Port Felicity. Despite these words, the fishermen decide to destroy the structure, but at that moment, oil explodes through the rig and onto the platform. The fishermen discover that the golden shrimp bed is huge; consequently, the conflict between the oilmen and the fishermen is resolved. Teche then convinces Steve that Stella was not involved in Philippe's plot, and the lovers finally come together.