In the distant future, a housewife, Enid Clinton goes out to the garage where her husband, physics professor David, is cataloguing his collection of historical artifacts. He explains that when he didn't get tenure because of his crazy theories about time travel, he stole the items using the powered time-travel suit. Enid says he's stupid for stealing trash. However, David warns that they can't use the suit to change history. Enid dismisses him as a loser and David activates his suit and leaves her, escaping into the time stream.
In the present at the Watchtower, Shayera and Wonder Woman cross paths at the cafeteria. Green Lantern and Batman, sitting nearby, note that Wonder Woman is still carrying a grudge. Batman wonders if Green Lantern is carrying anything and Green Lantern insists he's with Vixen now. He asks about Batman's relationship with Wonder Woman and Batman insists they're just colleagues... just as Wonder Woman comes up behind him. An intruder alert goes off in the dormitory and three heroes head there to find David breaking into Batman's quarters to steal his utility belt. Batman disarms him and David escapes into time. The Leaguers enter the time rift to follow him and find themselves in the 19th century in the Old West in Oklahoma. Three outlaws are there and try to rob them, saying that the Leaguers are in Tobias Manning's territory. Wonder Woman easily deflects their bullets and captures them. Batman finds a newspaper and discover they're in 1879. They realize that they need period gear and take the outlaws' clothing.
In the nearby town of Elkhorn, Tobias Manning is playing poker with gambler Bat Lash and several others when the Leaguers arrive. Bat wins against Tobias and it's clear one of them is cheating. Tobias draws a futuristic gun but Bat produces his own holdout gun and suggests they split the pot. Tobias' guns splits into six parts and Bat surrenders, Batman tells Wonder Woman to wait until they have a feel for the situation. Tobias orders his men to take Bat away to hang in the morning. When Batman stays out of trouble, Wonder Woman ignores him and prepares to free Bat at dawn.
Bat tries to break through the bars but the other prisoners, David Clinton, says it won't work. Their guard sees a ghostly green figure enter the jail and runs into a wall, knocking himself out. Green Lantern and the others arrive to free Bat. He insists on staying in town to finish things and the Leaguers explain that they're lawmen in town to capture Tobias. When they ask about futuristic technology, David speaks up and explains he arrived six months before they did. When he arrived, Tobias took his suit, went to the future to get advanced weaponry, and used it to take over Elkhorn. The outlaw uses David to explain the technology he can't figure out on his own. David agrees to help as long as they'll return him to his own time. Batman notices there's a surveillance camera in the corner and its time to go.
As the Leaguers leave, Tobias' men open fire and the Leaguers perpare to move. However, several local heroes move in: Jonah Hex, Sheriff Ohiyesa Smith, and El Diablo. They subdue the outlaws and introduce themselves. Bat explains he was there undercover to find out more about Tobias and the Leaguers are on their side. Sheriff Smith explains that he's lived in Elkhorn all his life and it was relatively peaceful until Tobias arrived with his advanced weapons. He easily ran Smith out of town and took over the place. He found Hex, Bat, and El Diablo to assist him in taking Elkhorn back. They're glad to accept the Leaguers' help.
The seven heroes ride toward Tobias' desert hideout. As Smith warns them to watch out for anything unusual, One of Tobias' men flies in riding a robot pterodactyl. Wonder Woman flies up to attack, defeating it. The heroes proceed to the ranch and robot cowboys attack. Green Lantern and Wonder Women take out the sentry guns while Batman swings in and subdues the robots. An outlaw rides out on a velociraptor and Wonder Woman takes it down. The heroes storm the enclosure and find themselves face-to-face with a tank. It doesn't last long against Wonder Woman but she's grabbed by one of several giant robots. They don't last long and Wonder woman breaks free of hers.
Smith calls Tobias out and the outlaw draws his six-gun six-shooter. The other heroes demolish the weapon and Tobias flees on a winged robot horse. Smith manages to leap on as the horse flies into the air and brings it down. Finally he and Tobias fight and Smith defeats his opponent and takes away the chronosuit.
Green Lantern disposes of all of Tobias' technology and David manages to get his hands on the chronosuit. He departs through a timerift and the Leaguers go after him. They lose David but find themselves in a futuristic city. A criminal street gang comes after them, saying they were expected. However, a new team of heroes flies down from the sky: Static, the futuristic Batman, and a winged armored warrior. The warrior sees Green Lantern and calls him "Dad."