In Abilene, Mayor Oliver is at the Dry Gulch Saloon and calls over the owner, Theodora, to remove the poster of Billy Coe, a reputed castle rustler and the losing candidate in the recent mayoral elections. When she refuses, the mayor appeals to Marshal Heck Thomas, who is playing poker with Bart. The marshal says that it’s Theo’s place and she’s doing nothing illegal. He’s retiring when Wyatt Earp arrives to take over as Marshal, and he doesn’t want any trouble while he waits. Meanwhile, Bart tries to get an IOU to cover his poker debts, and Theo refuses to give him credit. He finally puts up his watch as collateral to win the pot. A gunman suddenly shoots the marshal from behind, and B art shoots the killer dead. He confirms that the gunman was The Beasley Kid, and the townspeople figure that Billy Coe put Beasley up to it.
The townspeople want Bart to serve as marshal until Earp arrives. He refuses, but Mayor Oliver stops him from collecting the pot and threatens to arrest him for vagrancy. Bart quickly agrees, but only until Earp arrives. Bart then tries to collect his pot, only to discover that he lost, just as Mayor Oliver knew all along. Bart tries to form a posse to go after Billy Coe, but no one is interested in going with him. Bart says that it’s excellent, because Billy Coe will have to come into town and Earp will be there by then. However, Theo has more news for him: Earp won’t be there for six weeks.
Later, Bart is getting a haircut when Mayor Oliver comes in and tells him that Coe is in town. Bart reluctantly goes to confront the outlaw, who is at the Dry Gulch Saloon kissing Theo. Coe denies hiring the Beasley Kid to kill the marshal, and says that he’ll make something of her once he takes control of Abilene. Theo refuses, saying that she wants him to do it her way and become mayor. Coe walks out and finds Bart waiting for him. Bart suggests he stay out of town for six weeks so neither one of them will end up dead. After that, Coe will be Earp’s problem. When Coe doesn’t agree, Bart says that Beasley signed a confession before he died. Coe doesn’t believe it at first, but Bart insists and Coe draws a gun on him. He prepares to get the confession and shoot Bart, but Theo overhears the whole conversation and draws her own gun. She orders him out, and Coe says that he’ll be back. Once he’s gone, Theo points out that Beasley died instantly, and admits she was wrong to back Coe.
At the marshal’s office, Mayor Oliver wants Bart to arrest Coe now that he’s proven his guilt. Bart says that he couldn’t count on Theo to back him. When Mayor Oliver threatens to fire him, Bart immediately resigns and leaves. The mayor goes after him and insists that Bart hold to his deal. Before Bart can respond, a gunfighter gets out of the stagecoach. They recognize his gun as a Buntline Special, the one presented to Wyatt Earp. The townspeople gather as the man says that he’s Wyatt Earp, and that he got into town early. They explain that Marshal Heck was gunned down, and Earp prepares to go. However, when he hears that Bart shot down Beasley, he decides to stay and deputizes Bart. When Bart tries to refuse, Earp threatens to shoot him, and Bart hastily puts the badge on.
Later, Earp comes to see Bart at his hotel room and finds him packing to leave. Bart figures that Earp won’t draw on an unarmed man and keeps packing. Earp appeals to Bart’s conscience, explaining that his brothers and friends aren’t available to help him. Bart gives in, and Earp promptly borrows his $20 gold piece from him to let him play poker. He is soon playing and winning, and flirting with Theo when she takes a shine to him. Bart watches as Earp plays the next hand and bets $20. He gives away one of his two aces but manages to draw to an inside straight, much to Bart’s surprise. Later, Bart meets Earp outside and asks for his gold piece. Earp gives it back along with half of the winnings. They patrol the town, and Bart warns that it’s too peaceful. Earp is eager to let Bart deal with Coe when he shows up. They split up and Earp practices his fast draw. He can’t even manage to get the long-barrel Buntline out of the holster.
Coe and his gang ride into town and spot Earp. Earp starts to back away, yelling for Maverick. Coe wants it just between the two of them and draws. Earp trips and rolls on the ground, avoiding Coe’s shots. Bart arrives and Earp almost shoots him... and unwittingly hits a bushwhacker behind Bart. Mayor Oliver sees the whole thing from the saloon, while Bart fires on Coe and the others. They finally ride off and the townspeople come out. Earp wasn’t even aware that he shot the dead bushwhacker, but Mayor Oliver is glad to give Earp full credit for shooting a man without even aiming. Theo offers a round of drinks, and Bart tries to work out how Earp could have shot him.
Coe and his men retreat to their hideout, and the saloon’s bartender warns him that Earp is going to call in his brothers, and that Theo is sweet on him. The crooks get word that three of his men are riding in, and he tells the bartender to give Theo a message. The bartender passes on Coe’s warning that she either help him or take a bullet. Coe wants her to invite Earp up for breakfast that morning. Earp arrives to invite Theo downstairs for a cup of coffee. She invites him to stay in her room for coffee and the bartender quickly leaves and tells one of Coe’s men to climb up to a nearby water tower.
Earp invites Theo to join him on the couch so he can tell her something important. As she tries to confess that she’s working for Coe, Coe’s man sneaks up to the window. Earp doesn’t see him, and Theo leaps onto Earp’s lap to shield him. He assumes that she cares for him until he finally sees the killer. The man throws a knife and misses, and Earp yells for Maverick and runs outside. He tells everyone that Coe is coming and they all panic and run off the streets. Coe rides into town and realizes that Theo double-crossed them. Bart hears the commotion and comes out just as Earp trips and shoots the killer. Coe steps forward and shoots the gun out of Earp’s hand, and he runs to the saloon and uses Theo as a shield. The criminal grabs the Buntline and retreats, and calls Earp out at 3 o’clock that afternoon. The gang rides out and Mayor Oliver congratulates Earp on shooting the killer. Earp is eager to give all the credit to Bart and let him shoot Coe, but Bart says he’ll have to deal with Coe.
Later at the marshal’s office, Earp is practicing with a new gun when the real Wyatt Earp arrives. He’s heard that someone was pretending to be him, and the imposter explains that he borrowed Earp’s Buntline and Coe took it. They demand an explanation, and the imposter explains that he’s Archibald Walker, a bartender from Laramie. He was working the bar when Earp sent the telegram saying he wouldn’t get to Abilene for six weeks. Archibald wanted to be someone who was feared and loved, rather than a nobody. He tried to steal some of that respect and awe for six weeks, and Bart has to admit that he succeeded. Archibald admits that he’s lived more in the last few weeks than in his entire life. When Earp points out that he’s endanger everyone, Archibald admits that he doesn’t have all the answers, and Earp says that he’ll have to take on Coe. When he hears that, Archibald insists on shooting it out with Coe. Bart and Earp both disagree, and tell him to take the next stagecoach out of town.
Archibald goes to see the smitten Theo at the saloon. He tells her the truth and says that he’s leaving town, and Theo asks if she’s going to leave her to Coe. Archibald says that he doesn’t have a choice and leaves to meet Bart at the barbershop. When he sits down to have his distinctive Earp-style mustache and sideburns cut off, Elkins the barber calls him Earp and they explain that Archibald isn’t Earp, and that it’s Elkins’ life if he tells anyone. Bart goes to get the stagecoach ticket and runs into Doc Holliday. Doc is there for a shave and bath before he leaves town. He is trying to duck a young woman, Cassie Jones, intent on marriage, and asks Bart to tell her that Doc has left town. Doc goes into the back for a bath while Bart goes to get the ticket, and Archibald contemplates abandoning Theo. He then tells Elkins to trim his mustache like Doc Holliday’s.
At 3 o’clock, the bartender tells Coe that Doc is in town and backing Earp. The townspeople see Coe and his gang and run for cover. Archibald steps out, dressed as Doc, and hides when Mayor Oliver runs by trying to find Wyatt. The real Wyatt steps out and Mayor Oliver has no idea who he is. As Earp prepares to draw, Archibald comes up behind him and orders him into the marshal’s office at gunpoint. He locks him up and steps into the street to face Coe. Meanwhile, Bart sees the two men from his hotel window. As he runs out to stop Archibald, he runs into Theo and tells her what’s happening, and she declares that she loves Archibald.
One of Coe’s men is atop a nearby balcony. As Bart comes out, he spots the man and shoots him, hitting Archibald’s hat in the process. Coe goes for his gun but can’t get it out of his holster. He pulls the trigger Archibald thinks that he’s hit, and pulls the trigger, accidentally shooting Coe. Bart runs out and assures Archibald that he’s fine, and the townspeople gather to thank Archibald, who think he’s Holliday until they realize that he’s “Earp.” Doc Holliday comes out from the bath and demands his stolen clothing back.
At the stagecoach, Cassie has caught up to Doc Holliday, much to dismay. He’s not too happy that Archibald was impersonating him, but Archibald assures Doc and Earp that he won’t impersonate either of them ever again. Theo is happy that Archibald is alive and kisses him, and then asks him to write to her. Once he’s settled, Theo promises to sell the saloon and come live with him. The stagecoach leaves and Bart suggests that they play a game of cards... until he discovers that Archibald has stolen his cards. In the stagecoach, Archibald introduces himself to his fellow passengers as Bart Maverick and offers them a game of poker.