Jim rides into the mining town of Morning Glory, Arizona, accompanying a gold shipment. He goes to the Glory Hole and finds the claims inspector, Ben Victor. He explains that he has 2,500 pounds of gold dust to place in Ben’s vault. As they go to the office to deposit the gold, Brother Simon, a traveling hellfire preacher, bursts in to condemn the drinkers and gamblers. When some of the customers attack Simon, Jim comes to the preacher’s aid.
As Jim finishes off the last man, they hear a strange whirring noise outside. Everybody runs out to see a glowing ball of fire come down out of the sky and hit the ground outside of town. Simon insists that hellfire has come down from the sky and struck the town, just as he predicted.
Jim, Victor, and the townspeople go to investigate and find a glowing-red metallic saucer. When Jim approaches it, a voice tells him to halt. Simon steps forward and calls destruction on it, ignoring the warning, and an invisible force knocks him back. The door of the saucer opens and an attractive green-skinned woman emerges. She introduces herself as Morn and says that Simon wasn’t permanently harmed. Morn tells them that she and her crew are from Venus, and that they can speak English because Venusian females have a gift of translation. She gets a telepathic message from her sisters in the ship and tells Jim and the others that they are out of fuel. Her “sisters,” Pan and Alna, emerge from the ship, and Morn asks them for a fuel named “meldum.” One of her sisters brings out a sample: a sphere of gold, and Morn asks them for 400 pounds. When the townspeople express surprise, Jim explains that it is rare on Earth. Ben takes an interest on the jewels on her clothing, and she says that they are common on Venus. She and her sisters casually hand out the gems to Ben and the others, and he suggests that they may be able to make a trade.
Jim and Ben return to town and deposit the gold dust with the clerk, Byron Pettigrew. An Army convoy will be there in two days to pick up the gold. Ben invites Jim to the saloon for a drink and they pass Simon’s wagon. Simon himself is seated at a table, drinking heavily. The townspeople ask about the gems, and Jim tests them by successfully scratching a mirror. Ben is skeptical, but Artie is in the bar, posing as traveling jewelry salesman Dick DuJong. He confirms that the gems are diamonds, but only second-class stones. Artie leaves and Ben suggests that they trade the gold dust for the gems. Simon speaks up, insisting that the women are evil.
Jim strolls outside and secretly strikes up a conversation with Artie, who tells him that the gems are the real thing. They both figure it’s a con game, and Jim continues on his way. Three men quickly ambush him and knock him out, and two of them ride out toward the saucer with Jim thrown over his own horse. Jim wakes up en route, uses the hidden knife on his stirrup, and cuts himself free. One of them prepares to shoot him, but the other one says that if they use a knife, it will look more like the Venusians did it. As they attack him, Jim knocks them down, grabs one of their guns, and forces them to surrender. Once he knocks them out, Jim finishes cutting himself free, ties them up, and sends them back to Morning Glory on their own horses.
Morn emerges from the saucer and asks what happened. Jim assures her that his “playmates” are okay, and asks if he can rest inside their saucer. When she says that it’s not allowed, Jim gives her a kiss and she asks why he did it. He explains that a kiss is a gesture of friendship, and warns her that she’s mixed up in something serious. Morn asks what he means, and one of her sisters comes out and sends her a telepathic message. Morn says that she has to go inside and leaves. As Jim rides off, a peephole in the side of the saucer opens and someone watches him depart.
The next morning, Artie and Ben are leaving the saloon when the horses with the two unconscious thugs wander back into Morning Glory. Jim rides into town and goes into the saloon, and Ben advises everyone to avoid the Venusian spaceship during the night.
Later, Jim and Artie enter the saloon as Ben takes down all of the contributions of the townspeople’s gold. They end up with 150 pounds, well short of the 400 pounds needed. Ben turns to Jim for answers, and he notes that there is plenty of U.S. gold dust in the vault, but it belongs to the government. The assayer says that’s that, but Artie jumps in and suggests that they borrow the funds temporarily. Jim warns against it and leaves.
Later, Jim sits down and has another secret conservation with a nearby Artie. Artie concedes that Jim’s theory is right, and Ben and Wingo are encouraging the miners to steal the government gold dust. Once the miners blast into the vault, they’ll take the gold dust to the “pie plate,” it will somehow disappear, and the miners will take the blame for the theft. Jim suspects Ben, but admits that he seems too obvious. Artie heads to Ben’s office to put the soldiers on alert, while Jim goes to take Morn on a picnic.
That night, the soldiers on guard hear a sound in the alleyway outside the assay office. Pan and Alna are unconscious on the ground. Artie is there and comes out with the soldiers to investigate. They take the Venusian women inside They wake up and explain that they had an adverse reaction to Earth’s atmosphere. The Venusians then beg for the gold so they can return home. When Artie explains the gold isn’t theirs to give, the women take out “anesthesia projectors” and gas Artie and the two soldiers unconscious. Artie secretly dons a gas mask to protect himself, while Ben comes in wearing a gas mask of his own. He and his men open the vault and load the gold dust onto a wagon in the alleyway, and then drive off as Artie watches them.
Jim and Morn share a picnic basket and he explains the concept of fried chicken. She says that she’s feeling friendly toward him, and Jim notices that her “green skin” is rubbing off on her napkin. Morn swears him to secrecy and explains that she uses makeup to make herself look greener. She suggests that she’d like to stay.
Ben and his men load the gold dust bags into the pie plate, and then the two men ride off. Artie has followed them and waits until Ben and the women are inside. He approaches the pie plate, unaware that he is being watched from the hidden peephole. Artie starts to cut his way in through the underside, but someone clubs him unconscious with a tree branch.
Jim walks Morn back to the pie plate, and he hears Artie groaning inside. Morn tells him that he has to go, but Ben comes out and captures Jim at gunpoint. He escorts the agent inside and introduces the three women as the Courtney sisters. Artie is tied up, and his skin is dyed green. Ben explains that the chief believes it will add another bizarre note to the proceedings when Artie’s corpse is discovered. He then opens a curtain and reveals... Brother Simon, impeccably groomed. He takes a derringer out of a Bible and informs Jim that there’s a time to live... and a time to die.
Once Jim is tied up, Simon explains that they’ve rigged the pie plate with explosives. The explosion will go off in 20 minutes at 11 o’clock, simulating the pie plate taking off. Artie figures that they arrived in Morning Glory in a balloon with flares, using a hand-cranked noisemaker. Jim realizes that they’ll leave town in Simon’s wagon. Simon explains that they planned their operation knowing that Jim would arrive, hoping he’d testify as a Federal agent. The “force field” was a wire that the thugs hauled Simon back with.
Once Simon leaves, Jim cuts himself free with his boot-toe knife. When Ben comes in to check on them, Jim trips him, knocks him out, and frees Artie. Simon hears the noise and tells his men to ride on, but Jim comes out and tackles them. Artie fights with Simon and knocks him back into the pie plate, and the doors close. Jim finishes off his men and drives the wagon away, while Artie gets in the back and restrains the three women. Simon is unable to get the door open in time as the pie plate explodes. “Morn” comes out and assures Jim that she’s okay, tells him that her name is really Maggie, and kisses him. He informs her that she and her sisters are under arrest.
Later aboard the Wanderer
, Jim receives a telegraph message from Washington, confirming that Maggie got a year, while the others got 10-20. Artie, who is still green, thinks they should be hanged. Jim assures him that the dye should wear off in three days. They hear the same bizarre landing noise that Simon demonstrated earlier, and they look out the window. They see a blue fireball descend from the sky, and Jim wonders what it is. Artie refuses to discuss it, and suggests that they don’t tell Washington.