The Ricardos and the Mertzes are traveling via train to The Sands Hotel in Las Vegas where Ricky and his orchestra are slated to perform. Lucy shares with the Mertzes her plan to hunt for uranium, complete with a demonstration on how a Geiger counter works. She is forced to hide it under the seat when Ricky and Little Ricky return from the train's observation car. Ricky brings news that he has just run into Fred MacMurray who, too, is on his way to Las Vegas. A short time later, Fred MacMurray enters and is introduced to Lucy and the Mertzes. When Mr. MacMurray reaches down to tie his shoe, the Geiger counter goes off (his watch has a radium dial). To keep Ricky from discovering it, Lucy offers to tie his shoe for him, but ends up tying the laces of both shoes together. She quickly suggests that Mr. MacMurray leave; the Geiger counter goes off every time his watch goes near the it. Fred gets up to leave and falls. He's forced to hop out of the Ricardos' and the Mertzes' cabin.
At the hotel, Lucy is lying in bed thumbing through a magazine while Ricky gets ready to rehearse with the band. She leads Ricky into believing that she'll just lie around and catch up on her reading. When Ricky finally leaves, she prepares to get out of bed (fully dressed underneath her bed jacket)to get her Geiger counter, the maid comes in, mistakenly thinking that the room is empty. She apologizes and leaves just as Fred enters with a dummy copy of a newspaper he purchased from a novelty store announcing that Little Ricky has been elected sheriff. She gets out of bed and tells Fred to tell Ethel to hurry and get ready to go hunting for uranium.
Lucy gets the Geiger counter out, but jumps back into bed when she hears the door knob jiggling. As it turns out, Ricky has forgotten his conga drum and discovers that Lucy has a Geiger counter, which she unsuccessfully tries to convince Ricky is an "electronic popsicle." He also sees that Lucy is fully dressed underneath her bed jacket. Ricky emphatically forbids Lucy to go, but the Mertzes enter the Ricardos' hotel room and Lucy's plans to go uranium hunting--for the time being--are kaput.
Later, Lucy confides to Ethel that she's figured out a way to convince Ricky to let her go hunting for uranium. She arranged with the people at the novelty store to print up dummy copies of the newspaper announcing that there's a big uranium strike right outside of town. Ethel tells her that Ricky would never fall for such a story, so Lucy agrees to abandon the idea and tosses the paper in a wastebasket. The maid enters the room as Lucy leaves to get ready for Ricky's show. The maid sees the paper in the trash can, reads the headline and excitedly tells the bellhop. Meanwhile, Lucy finds a distraught Fred MacMurray in the lobby of the hotel. He has just lost a hundred bucks gambling and fears telling his penny-pinching wife about it. She offers to help him, when suddenly the entire hotel is abuzz with the phony news of the uranium strike. Even Ricky gets wind of this news and tells Lucy. The Ricardos, the Mertzes and Fred MacMurray all head to the desert in their quest for uranium.
As soon as they get there, Lucy tosses the sample piece of uranium. Soon, the Geiger counters of the Ricardos, the Mertzes and Mr. MacMurray go off and the five begin arguing over who found the little chunk of uranium first. The five finally agree to split the $10,000 three ways--Fred MacMurray and the Ricardos will get $3,333, while the Mertzes-- getting the extra dollar--will get $3,334. Concluding that the claims office will be closed by the time they get there, they decide to camp out for the night and get up early the next morning to head for the claims office. A couple of passers-by with mules ask the status of the group's uranium hunt. Lucy unwittingly begins to discuss tell them, but Fred interrupts, warning that in a situation like this, no one--not even one's best friend--can be trusted.
Later that night, while everyone is asleep, Fred Mertz goes to the truck to get a cap because his head is cold. The younger Fred spots him and asks the Ricardos whether the elder Fred would try to cheat the gang. The Ricardos dismiss the notion as ridiculous, which makes Lucy suspicious of of the younger Fred. She shares these suspicions with Ricky, as well as the fact that she is aware of Mr. MacMurray's need to get extra cash to cover up his recent loss at the casino. Ricky refuses to buy into it and the Ricardos go back to sleep. Later on, upon hearing coyotes howling, a terrified Lucy suggests she and Ricky sleep in the truck. As they gather their things, Ethel spots them, mistakenly thinking that the Ricardos are trying to leave everybody high and dry in the desert and beat them to the claims office. The younger Fred and the Mertzes follow the Ricardos, who explain that Lucy was afraid of the coyotes and wanted to sleep in the truck. Fred and the Mertzes also suggest sleeping in their respective vehicles, but everyone agrees to just stay put when suspicions of each other continue to mount.
The next day, the Mertzes crank up their old jalopy of a truck to warm it up so they won't be left behind when everyone departs for the claims office. While Fred cranks the truck, Ethel, not knowing how to drive it, runs amuck, with Fred running after her. The Ricardos awaken, see the Mertzes taking off and follow behind. Fred MacMurray sees the Ricardos taking off and goes after them.
Ethel runs into a small tree, and Fred Mertz finally catches up. The Ricardos speed past, taunting the Mertzes. The Mertzes' truck is the slowest of the three, so Ethel resorts to throwing objects at Mr. MacMurray and the Ricardos to thwart their attempts to pass them This scheme works, but not for long. Mr. MacMurray and the Ricardos get pulled over by a state trooper, leaving the Mertzes to continue back toward town. They run across a detour sign. Before taking the detour, however, Ethel points the sign in the wrong direction. As a result, the younger Fred ends up stuck. The Ricardos ruthlessly pass him by. But their progress is stopped while they wait for a train to clear the crossing. The Mertzes catch up and the everyone is shocked to find the younger Fred maneuvering his way back to Las Vegas on a handcar right behind the passing train!
Fred MacMurray arrives at a gas station and uses the washroom. Shortly after, the Ricardos arrive to get gas and have their tires checked. Not too long after, the Mertzes arrive, and the elder Fred ties their truck to the back of the Ricardos' truck. Fred MacMurray hides in the spare tire on the back of the Mertzes' truck. The Ricardos continue their ride back to Las Vegas, and can't figure out how the Mertzes are able to catch up in spite of their high rate of speed. Ricky finally pulls over after realizing that the Mertzes are indeed attached to their truck. The Mertzes are equally surprised to find the younger Fred emerge from the spare tire of their truck. The Ricardos then prepare to leave Fred and the Mertzes behind, but can't because they're stuck. The fellows with the mules happen by and end up being talked into loaning everyone their mules. Within moments the Ricardos, the Mertzes and Fred arrive at the claims office in the hotel. Ricky hands the claim adjuster the uranium sample that everyone "discovered," and is revealed that everything was just a big misunderstanding and no one was trying to be a jumper. June Haver arrives and Fred decides to tell his wife about his $100 loss, but quickly tells her that he stands to get a third of $10,000. After examining the uranium sample, the claims adjuster says that it is not comprised of limonite--a mineral widely found in Nevada, but of batholith, which is found primarily in Montana. He further observes that the sample looks like it came in a Geiger counter kit. Lucy explains that she threw the sample away as soon as she got out of the car in the desert. Everyone begins to realize that the sample the claims adjuster was examining was the sample Lucy had thrown away. It's also revealed that the story about the so-called "uranium strike" was a hoax, planted by a "tall, redheaded woman." Lucy gets the evil eye from everyone and she makes a hasty exit on one of the "borrowed burrows." Just as June is about to tear into her husband about the $100 he lost gambling, he jumps aboard one of the mules behind Lucy and they take off.