Calamity Jane is unexpectedly released from a sheriff's jail when two government agents, under the guidance of Governor Johnson and Commissioner Emerson, enlist her help to expose a gun-running operation near Buffalo Flats. They believe using a legendary frontier gunslinger and a bold woman will give them the leverage they need, and, in exchange, they offer her a full pardon for her past misdeeds. The plan calls for Jane to travel to Port Deerfield, pose as a married couple with another agent, and join a settler convoy heading toward the gun-smuggling zone. Their infiltrative setup hinges on a clever blend of grit, disguise, and audacity.
The true mastermind behind the scheme is Jasper Martin, Johnson’s secretary, who hides behind a veneer of civility while pulling the strings from behind the scenes. Jane soon discovers that her partner in the operation, a federal agent named Jim Hunter, has been killed, and she becomes the target of assassins. After surviving an ambush, she befriends a traveling dentist on the run, Peter "Painless" Potter, and—seeking safety and cover—marries him to secure his cooperation and to keep her cover intact as the wagon train makes its way toward the danger zone. Little do the smugglers know that Potter’s presence also serves as a useful decoy for the dangerous game ahead, and they themselves join the trek, intent on delivering a stash of dynamite and tracking the government foe they believe is after them.
Tensions rise when Potter inadvertently leads part of the wagon train into Indian territory, and the group finds themselves under attack at a remote log cabin. Potter hides in a barrel and fires from his concealment, while Jane quietly picks off several enemies from within, a display of opportunistic courage that bolsters Potter’s own reputation in the smugglers’ eyes.
Upon reaching Buffalo Flats, Jane collaborates with Hank Billings to locate the dynamite’s delivery point. The smugglers hatch a plan to turn Potter into a liability, and a volatile clash with the notorious gunslinger Big Joe, played by Big Joe, tests Jane’s improvisational courage. Although she contemplates letting Potter fall to the snare of the conspirators, she chooses to keep him close as a decoy and, more importantly, as someone she has begun to care for.
The plot thickens when Billings reveals that the dynamite is hidden in the undertaker’s shop. Before he can report the detail, he is murdered with an arrow, and Jane must decide how to proceed with Potter. They are soon captured and taken to the Indians’ encampment, where the medicine man, Wapato, threatens Potter with a hideous punishment. His plan to tear the pair apart with a crude trap backfires, catapulting Potter into the forest instead and earning the medicine man a banishment from the camp. Potter, ever resourceful, seizes the medicine man’s clothes as a disguise and waits for the right moment to strike.
In a daring sequence, Potter slips through the camp, ignites a powder trail with his improvised disguise, and triggers a cascade of explosions that damage the smugglers’ weapons. The chaos provides the escape route Jane and Potter need, and they sprint to Potter’s wagon, loaded with dynamite, with their pursuers in hot pursuit. A lit dynamite stick is dropped, forcing the couple to abandon the wagon just as the smugglers close in—and, in a climactic blaze, the explosives detonate, wiping out their quarry.
With the mission secured, Jane and Potter embark on what’s supposed to be a honeymoon—though the film preserves its running gag by letting Jane end up caught in one of the comedic twists that punctuate the story. The caper blends frontier bravado, screwball chemistry, and a crowd-pleasing mix of peril and punchlines, concluding with a note of ironic romance at their destination, even as the joke lands squarely on Jane in the end.
