In Sicily, Napoleon and Illya are spying on an international conference of mobsters led by Uncle Giuliano. The American representative, Giuliano's nephew Frank Cariago, arrives with his bodyguard Angelo. Illya, disguised as a winemaker with a basket of grapes, slips past Angelo and listens at the wall. In the conference room, Giuliano is complaining that Frank hasn't kept control of Las Vegas despite their role in creating it. Frank insists that he'll soon take care of the problem despite the fact that he's already lost twelve men, and Giuliano gives him a week to take control or Frank will become number thirteen.
Angelo spots Illya at the wall and advances on him, and Illya dumps his basket on the bodyguard. He steals a scooter from a passing messenger and drives past Napoleon's wagon. After Illya jumps off, he gets in the wagon and gives Napoleon his fake beard and shawl, and Napoleon disguises himself as a woman while Illya drives the wagon past the unsuspecting mobsters.
Act I: My baby wants Technicolor-Cinemascope, my baby gets Technicolor Cinemascope.
Back in New York City, Waverly is disappointed that the agents didn't learn what Cariago is up to. He tells them that Cariago has returned to his home in Beverly Hills and sends them to spy on the mobster.
At Cariago's estate, Illya goes in posing as a pool repairman to plant bugs near the pool. Cariago's girlfriend Ginger comes out to sunbathe and immediately notices Illya. She flirts with him, hinting that he isn't the first repairman that she's come onto, but Illya resists her charms. Ginger mentions that she reads the show biz magazines and Illya distracts her by asking if she's an actress. The woman explains that she's a former go-go dancer and that Cariago is going to make her a star in a major movie.
Cariago and his men come out, all of them injured after Giuliano had his men in Sicily teach them a lesson. Illya quickly slips back to the van where Napoleon is listening in, while Ginger shows Cariago an article about how famous director Sheldon Veblen is closing down production of his new movie, Sodom and Gomorrah, because of lack of funds. Cariago has no time for her ambitions and worries that he only has four days to get Las Vegas under control. As Ginger walks away, furious, Angelo reads the article and suggests that Cariago take advantage of it. Switching gears, Cariago calls Ginger over and promises to get her into the movie. She hugs him, squeezing his broken arm, and he shoves her into the bush where Illya planted one of the bugs. Cariago sees it fall and muffles it in his hand, and then says that it's from U.N.C.L.E. and that Illya must be working for them.
Later, Sheldon is in Las Vegas filming the last scene of his epic before he runs out of funds. Napoleon and Illya arrive, posing as a movie magazine reporter and his photographer, and Sheldon assures Napoleon that the cast and crew are one big happy family. Harry the process server storms in with a court order to impound all of the equipment to cover Sheldon's debts. Sheldon gives a speech thanking everyone for their efforts but admits that his film will never be finished.
Cariago and his men come in and the mobster introduces himself, while Illya keeps out of his sight line. The mobster sends Harry away and then confirms that Sheldon needs $2,000,000 to go back into production. Cariago tells Napoleon to write an article informing his readers that Sodom and Gomorrah has a new backer. When Napoleon and Sheldon both wonder why Cariago is financing the film, the mobster brings Ginger in and Sheldon realizes what he'll have to do for the money.
Realizing that Ginger can identify Illya and probably will; the agents try to get out. However, Cariago insists that Illya take some photos, and Ginger recognizes the agent as the pool repairman. The agents try to leave but Angelo and his men quickly grab them.
Act II: More action! I want impact!
Much to the agents' surprise, Cariago tells Angelo to treat them gently because they're from U.N.C.L.E.... Uncle Giuliano. Napoleon and Illya are soon enjoying VIP chairs and canapés while they watch Sheldon film his first scene with Ginger. It's a kidnapping scene in her character's bedroom and her husband and his bodyguard storm in to fight the kidnappers. Sheldon tries to get her to emote without success and the director soon calls a break. He goes to the editing room to watch Ginger's screen test, and Napoleon comes in. The agent tries to find out how the movie ends but Sheldon will only say that it ends like it does in the Bible.
Illya goes Ginger's dressing room to check the script and see if it has the ending. Ginger comes in and starts to flirt with him, but he distracts her by handing her a hand mirror. As she primps, Illya asks if she knows the ending and Ginger figures that her boyfriend is the only one who might know.
On the set, Cariago demands that Sheldon tell him the end of the movie or he'll withdrawal his funding. Sheldon finally whispers it to him and Cariago congratulates him. He then checks on Napoleon, who says that Cariago's security was too tight for them to find out his planned. Napoleon offers to put in a good word with Giuliano about the security, pleasing Cariago. However, they're interrupted when Angelo informs Cariago that Giuliano is calling.
Cariago goes to Sheldon's private office and admires his model of Las Vegas. Giuliano complains that Cariago is wasting two million dollars on a movie for his girlfriend, but Cariago explains that his real plan is to use the movie to wipe out Las Vegas. For the end of the movie, Sheldon plans to blow up Las Vegas with an atomic bomb. What he doesn't know is that Cariago is substituting a real nuclear bomb for the dummy Sheldon had built. Cariago sets off the scale explosion on the director's model and laughs in triumph. Giuliano congratulates him, assuming that he succeeds, and Cariago assures his U.N.C.L.E. that he's taking care of the two men he sent. His uncle says that he has no idea what he's talking about and figures that Napoleon and Illya are spies.
Act III: Put the mistake in the tub.
As Sheldon tries to film the bedroom scene again, Cariago and his men come running in. Illya and Napoleon realize that their cover is blown and they run into the bedroom set. A real fight breaks out around the fake fighters, while Sheldon tries to clear the shot. The agents finally run out, and Napoleon loses his gun to a stray shot. The mobsters finally bring them to ground in a prop warehouse and chain them above a tub of liquid concrete. When Illya mouths off to him, Angelo has him dropped into the concrete and tells Napoleon that they'll do the same to him once Cariago interrogates him.
Cariago visits the scientist he's hired to create an atomic bomb, but the man warns him that it will take time. Giuliano comes in with his men and explains that since he figured his nephew would mess things up again, he brought his own bomb. His men wheel it in just as Ginger arrives, complaining that Cariago left her in the car. Cariago blurts out her plan to her and Giuliano, disgusted with his nephew, has his men lock Ginger up in a closet.
Act IV: That's what I call a jackpot.
Angelo and his men leave once the concrete hardens and Napoleon slips his bonds. He runs over to the tub but confirms that Illya has used a straw to breathe.
Waverly arrives in Las Vegas and calls the agents. As Napoleon chisels Illya out, Illya admits that they don't know what Cariago's plan is. Their superior tells them that Giuliano is somewhere in the U.S.
Cariago and his men take the bomb out to a bomber, and Sheldon and his film crew arrive. Sheldon assumes that the bomb is his and starts pounding on it when he realizes it's not the fake bomb he had built. Cariago finally stops him and Sheldon realizes that it's a real bomb, and the mobsters lead the director away.
Ginger manages to slip the latch on the closet door. As she drives away, Napoleon and Illya wave her down and she tells them about Cariago's plan. They commandeer Ginger's car and drive for the airport.
After Sheldon faints, Giuliano and his men leave him lying on the runaway as they taxi down the runway. The agents arrive and have Ginger drive underneath the bomber, and then climb up on the ladder. The bomber lifts off and Ginger drives over to Sheldon as he wakes up. Rather than call the police, Sheldon goes off to find a plane so he can film the real destruction of Las Vegas.
Waverly wanders into a casino to watch the gamblers. One old lady asks Waverly to play her machine for her and break the hex because she's leaving.
Napoleon and Illya fight Cariago's men in the hold, and Illya falls on the bomb. When Napoleon breaks into the cockpit, Giuliano releases the bomb... with Illya aboard. Meanwhile, Sheldon and Ginger have found a pilot and are filming from behind.
Napoleon takes out Giuliano's bodyguard and points out that if the bomb goes out then they'll be caught in the explosion. Giuliano tells him that the atomic bomb was Cariago's plan: he just plans to drop a giant stink bomb on Las Vegas and drive out the competition.
Illya manages to put on a parachute that he grabbed before the bomb dropped. He climbs up to the nose and unscrews it, and realizes that it's a stink bomb as the stench floats up into his face.
Waverly spins the machine and loses, and spins it again.
Realizing that the bomb is a dud, Illya leaps clear and chutes down to safety. The bomb hits the casino where Waverly is playing and goes through the roof just as he wins a jackpot.
Later, Sheldon's movie premieres and makes millions. Giuliano and Cariago are in jail in Sicily, and Napoleon stops by the premiere to tell Sheldon and Ginger that the mobsters won't be coming back anytime. Ginger poses for the photographers while Sheldon suggests that he could use Illya in his next movie. Napoleon explains that his partner has other matters on his hand, slips away, and calls Illya. Illya is at U.N.C.L.E. HQ undergoing decontamination to remove the stench.